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1. www IPCAPEXEXPO or February 2010 Issue 235 N N THE WORLD Benefit from the industry s premier technical conference half day courses Designers Day and IPC standards meetings Solve your manufacturing challenges visit hundreds of exhibitors and meet thousands of peers and industry experts in electronics manufacturing Focus on critical areas such as high speed signal integrity PCB design materials compliance design for manufacture and embedded technologies Pre register for free exhibit hall admission and take advantage of free keynotes posters forums and networking events characters representing hex values Although the datasheet is sparse and not translated well into English it appears that ID1 through ID8 form a 64 bit code and ID9 and ID10 are the checksum of the previous 8 bytes How ever the datasheet also mentions XOR which is used for CRC error checking not checksum error calculations In any case I considered all 10 characters as the ID code I bought my reader several months ago Futurlec now carries a slightly dif ferent model It costs about the same and mounts in the same fashion but it has fewer interface wires and is black rather than white But I suspect that it operates identically VINCULUM VDRIVE2 FTDI spun off a subset of its USB devices into what it calls the Vinculum line Vinculum is Latin for a bond or a tie and that is what these devices do they tie USB devic
2. Internet Embedded MCU IMCU W7100 1 64KB Flash j I F Manager 11 0592 MHz Register Manager UDP TCP ICMP X m JoBpubpw Aiowsay WVudd X3 X1 92 PPPoE ARP P 802 3 Ethernet MAC e H W TCP IP MAC 10BaseT mph 1 100Base TX Ethernet PHY 18V MilMenager CSMA CD e Fully software compatible with standard 8051 25 Mit So e Pipelined architecture with standard 8051 re e 64K Bytes e Flash memory e 64K Bytes SRAM memory e 100 LQFP Lead free package e Single Chip Serial to Ethernet Gateway iMCU7100EVB cs EST Pa e TCP lookback Ey o n e e UDP lookback E Me My d e DHCP Client e DNS Client e Serial to Ethernet Gateway e Internet LCD display e HTTPC e Telnet RS232 RJ45 32GPIO LCD Available at www WIZwiki net Av www WlZnet co kr 7n et www WIZwiki net Choose Your Own Design Adventure hen I was a child I read a few of the books in Bantam s Choose Your Own Adventure series The point was to make decisions that would influence the course of the tale Decisions were presented in a simple format Example To do X turn to page 5 To do Y turn to page 10 As a book s main character I d drive the story by turning to certain pages and then reading on Some choices led to situations in which the main character was rewarded Other choices led to negative scenarios such as the main character s death Thus each book had a few possible endings Hmm That s kind of lik
3. 842 Boggs Avenue Fremont ca 34539 SS TET Edd XL MaxSonar Ultrasonic Ranging is EZ XL MaxSonar Products e High acoustic power Low cost e Low power 3V 5 5V lt 4mA avg 1 cm resolution e Serial pulse width amp analog voltage outputs Real time auto calibration with noise rejection No dead zone XL MaxSonar EZ e Choice of beam patterns Tiny size 1 cubic inch e Light weight lt 6 grams XL MaxSonar WR p67 e Industrial packaging a e Weather resistant e Standard fitting e Quality narrow beam www maxbotix com ez_ The Smart Display makes integrating a GUI ez Versatile Programming LCD module USB SPI RS232 TTL Interfaces Bright 350 Nit LED Display 320 x 240 Integrated Touch Screen LUA Scripting Language capable For stand alone embedded apps Memory 3 8 MB SD to 2G ezLCD s are also availabl in 27312 5 6 6 4 8 07 I0 te Sree L D pin ezL b 1032 Call for Custom Display Configurations wwweerthled cous February 2010 Issue 235 m m ELECTRONIC The Circuit Cellar college program namana puts quality engineering information ao in the hands of your students every month Sign up now to get AATEENUTYS WEEKTENC m 7 Circuit Gellar distributed to your E class this semester coe n To update your professor account or to find oul more about our college program visit geww circuitcellar comproducts col
4. int2fp T input audio in FP audio in 15 61 0 fpZint f output audio out int audio out FP 0 assign audio out tfaudio out int 6 hO MAC operation fpmult f c x v f coeff x value f coeff f value fpadd f mac add f mac new f mac old f coeff x value state variable reg 3 0 state oneshot gen to sync to audio clock reg last clk HIE ET EE YEEEPE4y ATI TIT SAT IT ITI TT ITI IT I IT Run the filter state machine FAST so that it completes in one audio cycle always posedge state_clk begin if reset begin State lt 4 d15 turn off the state machine end else begin case state 1 begin set up bll x n f mac old lt 18 q0 f coeff lt bll f value lt audio in FP register input xln audio in FP next state state lt 4 d2 end 2 begin set up b12 x n 1 f mac old lt f mac new f coeff lt b12 f value lt xl n1 next State Continued on p 52 WwwW circuitcellar com CIRCUIT CELLAR 2 February 2010 Issue 235 February 2010 Issue 235 incoming audio signal through a two four or six pole infinite impulse response filter I figured that the Listing 3 Continued from p 51 state lt 4 d3 a end actual audio input plus the dynamics n of the filters themselves would pro begin duce a large range of different floats set up bl5 x n 2 f mac old lt f mac new When the output of the filt
5. DESIGN OVERVIEW Before examining the details of the various modules used in the project refer back to Figure 1 The RFID reader is a low cost module that signals the presence of a low frequency RFID tag by sending the tag s unique 10 hex charac ter ID code via a 9 600 bps RS 232 link Upon authentication you interact with 24AA1025 1 024 Kb PC flash memory devices yielding a total storage capacity of 256 KB of nonvolatile memory The controller opens a solenoid valve for an interval timed to dispense the desired volume of liquid nitrogen An RTC circuit is needed because the time and date of each transaction must be stored with its record The ATmega series of microcontrollers does not include a dedicated RTC module featur ing a separate battery back up power supply pin Therefore I chose the com mon Maxim Integrated Products DS1307 PC RTC chip with a 3 V coin cell for back up power Transferring the data from the transaction tables stored in the controller s PC flash memory over to a remotely located PC is accomplished with a USB flash drive The flash drive is interfaced to the microcontroller via the Vinculum VDrive2 module This mod ule communicates via a full duplex seri al data link All the firmware needed to work with the USB flash drive s FAT32 file structure is handled by the VDrive2 It does so in response to ASCII com mands sent to it via its serial link Because the RFID reader and the VDrive2 modules are ne
6. Q N CIRCUIT CELLAR e WWW circuitcellar com rate The code is summarized as fol One 2009 student project used the pipeline worked another good test for lows One convert the 16 bit integer floating point routines to implementa the floating point routines although audio codec input to floating point polygon rendering pipeline on the 9 bit resolution on the mantissa was a Two wait for the next 48 kHz audio FPGA Penmetcha and Pryor The little low for good z buffering i clock edge to start the state machine Three compute the first floating Bruce Land bruce land cornell edu is a Senior Lecturer in Electronics and Com point SOS as puter Engineering at Cornell University www nbb cornell edu neurobio land This yl n bl1 x x n b12 x x n 1 b13 x year he s teaching three courses one covering microcontrollers as components in x n 2 al2 x yl n 1 a13 x yl n 2 electronic designs one dealing with designing FPGA circuits for embedded applica tions and one covering electronic bio instrumentation Bruce also runs the Energy where x n is the input at time n and Conservation and Control Project www ece cornell edu aca meng energy cfm in yl n is the output at time n Four the Cornell School of ECE update the filter state for the next time step Five compute the second floating point SOS as D y2 n 2 b21 x yl n b22 x yl n 1 23 x PROJECT FILES yl n 2 a22 x y2 n 1 a23 x
7. Ultra Reliable w 128MB ECC RAM j with Floating Point Unit POE ready Dual execution unit double precision FPU Multifunctional PC 104 connector 12K LUT customizable FPGA 512MB NAND Flash 1 USB Host 1 USB Device 12 Mb s jill Boots Linux 2 6 in lt 2 seconds PE i b dt z Ge NEN a i B po T d a ITI Fr a Ea E J IT L i Sr A 3 7 a ni 2d E Mas tS ce RT umm o qui Lr A Fanless 4W sleep mode 1mW Regulated 5 28V power input 2 10 100 ethernet 2 SDHC sockets 4 COM ports a 5 10 bit ADC SPI amp DIO a RTC amp WatchDog RS485 RS422 2 DMX Channels shown w optional SD Card 22 Technologic A Sysbems We use our stuff Visit our TS 7800 powered website at www embeddedARM com February 2010 Issue 235 flash drive is practically negligible the transaction data is not Mounting two small PC flash memory devices on the controller board was more practical than worrying about a cabinet with a locked access door It also helped that Microchip had sent me some free sam ples of the 24AA1025 flash devices RFID TAGS amp READERS RFID tags come in various packages sizes and prices Some readers can cost thousands of dollars depending on their ei Lm LN a eI B Lio o WE intended uses My cost constraints meant that I had to find tags or cards worth less than a 1 as well as a compa rably low cost reader In an RFID scheme the reader gener a
8. in the AES standard don t have the usual meanings For example adding two or more bytes together is just an XOR Listing 1 This is the ALU that performs all of the AES operations for the data Some of these operations are also used for the Key expansion KKRKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK w register next input a KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKE always aluop_reg or w_reg or x_reg or y_reg or z_reg or key_reg begin casex aluop_reg AOP_SBOX w reg nxt sbox w reg 31 24 sbox w reg 23 16 sbox w reg 15 8 sbox w_regl7 0 AOP ISBOX w reg nxt ibox w_regL31 24 ibox w regL23 16 ibox w reg 15 8 ibox w reg 7 0 AOP SHROW w reg nx z_reg 31 24 y reg 235 106 x_reg 15 8 w_reg 7 0 AOP_ISHROW w reg nx ix reg 31 24 y reg 23 16 z reg 15 8 w_regL7 0 AOP_MXCOL mixcol w reg invmixcol w reg w reg key reg 31 0 w reg AOP IMXCOL w reg nx AOP ADDKEY w reg nx default w reg nxt endcase end t t w_reg_nxt t t xxkkkkkkxkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkxkkxk x register next input KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKE always aluop_reg or w_reg or x_reg or y_reg or z_reg or key_reg begin casex aluop_reg AOP_SBOX x reg nx
9. lt difference lt 0 5 Shift the mantissa left until the high bit is set while decre menting the bigger exponent once per shift to become the output exponent The sign is the sign of the bigger input CONVERSION It turns out that converting from integer to float is fairly simple I assumed 10 bit 2 s complement inte gers since the mantissa is only 9 bits but the process generalizes to more bits Save the sign bit of the input and take the absolute value of the input Shift the input left until the high order bit is set and count the number of shifts required This forms the floating mantissa Next form the floating expo nent by subtracting the number of shifts from step 2 from the constant Listing 2 Verilog describing a fourth order filter generated by a Matlab Octave script Filter cutoff 0 100000 Filter cutoff 0 200000 IIRAsos filter4 audio out filter4 out audio in audio inR bll 18 h10300 p12 IS hl0500 DL CIS HIOSO0J d 18 RIOSZAJ is X19 h30185 bel XJIS NIO300 022 x18 h3050D bz CIS hlI0300 deg IS mLUSBCO des CIS hs0lbBO gain 18 hF749 state cIKkCAUD CTRL CLK lr cIKCAUD DACLRCK Feset reset 5 end filter 137 or Oh89 of shifts Assemble the float from the sign mantissa and exponent Converting back to integer is similar ly simple but no overflow is detected so scale carefully If the float exponent is less than Oh81 then
10. mul_Od inpL7 0 mul 09Cinp 15 8 mul 0eCinpL23 16 mul 0bCinp 31 24 mul 09C1npL7 0 mul Oe inpLi15 8 mul ObCTnpL23 16 mul Od 1npL 31 24 mul Oe inp 7 0 mul ObCinp 15 8 mul 0dCinpL23 16 mul 09Cinp 31 24 state machine runs forward in the case of encryption and backwards in the case of decryption One of the primary design goals for the AES algorithm was that it be easy to implement in software on an 8 bit machine This was because the prede cessor to AES was fiendishly difficult to implement on such a machine The DES algorithm used odd length bit shifts and operations that were not byte aligned In this regard AES suc ceeded admirably EXPANDING THE KEY Compared to the encryption and decryption operations key expansion seems much more complicated This is okay though because the key expan sion really only needs to be done once for a given cipher key The key expansion algorithm takes the original 128 bit key and expands it into a total of 1 408 bits It uses the sbox operation from the encryption algorithm but only on a 32 bit word In fact all of the operations required for key expansion operate on 32 bit words generating one new word at a time This algorithm seems to have been opti mized for a software implementation It is shown in Listing 7 again in pseudocode As I mentioned the first round key is just the original cipher key This is the starting value for the loop t
11. s manual and files www opencores org eee PIC16F84 Microcontroller Microchip Technology Inc www microchip com XC2S200E Spartan IIE FPGA Xilinx Inc www xilinx com CIRCUIT CELLAR www circuitcellar com 2 ch re standalone USB bench scope 315 499 2 ch 40 1 00 200MS s 8 bit scope range with 5 10 25MHz 246 Packet Master USB 1 1 2 0 analyzers and generators 699 USB2 0 speed 16 bit digital pattern or arbitrary waveform generator Wireless Data Loggers j Log and display temp hum volt event time or pulse counting data USB to 12C Drop in solution connects PC to I2C SMBUS 32 I O lines 89 USB board adds 55 I O and 5 x 10 bit A D inputs 1 x 10 bit analog O P unique aBeil infagsaelig cam BBB 75RELIG 5022S PDS6062T E 2 ch 1GSa s 25GSa s equiv 50 100 MHz scope 595 795 PD 1022MN HDS2062M 2 10 25MHz USB powered scope in a probe Up to 100MS s 193 280 Scope Logger PS2203 4 5 2 ch DSO 16 bit DSO FFT VM logic analyzer standalone 24 I O 16 Ch Logic Analyzer B d Intuitive full featured 16 ch 4MB 200MHz sampling memory 279 I2C Xpress USB12 480 500AG Wave Xpress Versatile USB 2 0 I2C protocol exerciser and analyzer Mini logger with built in temp hum pressure 3 axis accel sensors FTDI USB ICs USBI2CIO Popular UART and FIFO chips Upgrade Legacy designs to USB PoKeys55T No OS n
12. The new NtelliJet series of low profile low acoustic coolers uses rapid fire pulses of turbulent air produced by an oscillating diaphragm working between 50 and 200 Hz to cool heatsinks and surrounding components The features of the NtelliJet cooler present an entirely new concept of thermal cooling ability In addition to ultra high reliability and low profile height max 15 mm there is also a total elimination of mechanical wear dirt and dust clogging The new series is also immune to shock and vibration and it provides an impressive 100 000 hours of life at 60 C The NtellJet is ideal for focused thermal require ments when cooling is needed for specific chips or areas of coverage The NtelliJet offers a flexible alternative for fans across a large range of industrial applications and designs Designed for directed cooling the NtelliJet optimizes heat exchange through the use of turbu lent high velocity jets The vortex dominated flow enhances small scale mixing near the heated sur faces to yield higher effective heat transfer at low vol ume flow rates compared to conventional air movers The NtelliJet flow is created using patented actuator technology and proprietary fluidic packaging expert ise The system wide heat removal takes advantage of the ejector effect inherent to high momentum jet flows As it operates the NtelliJet module expels high momentum pulses of air Each pulse of air entrains or pulls nearby ambient air
13. You could simply send it several times and recover the error free message either with a checksum added to each message or with majority Input data Eg Bite LIA Lil tA Ln vote This method even if it isn t very efficient can be enough for simple sys tems but linear block codes are better Although there are a zillion other linear block codes Golay BCH Reed Solomon and so on I ll focus on the simplest Hamming codes so you can see how such an FEC code actually works Such codes are easy to implement in hardware and they re used in error correcting memories ECC for example Figure 5 shows how a Hamming FEC code is generated on the transmitter side The encoded message length must be one less than a power of two i e 7 bits 15 bits 31 bits etc I used 7 bits for simplicity Firstly number each bit position with its binary repre sentation 001 010 011 etc Each bit with a binary position containing only one 1 must be reserved as an FEC bit All the other bits can be used to trans mit data Here the bits in position 001 010 and 100 will be FEC bits and the four other bits will be data bits This Hamming code is then called Hamming 7 4 as 4 data bits are transmitted in a 7 bit block To calculate the value of a given FEC bit e g the one at position 010 just calculate the parity of all data bits which have a 1 in their address at the same position e g 111 110 an
14. facing in the past relied mainly on either serial or paral lel ports for simplicity and ease of control And then the universal series bus USB came along The USB brings uniformity to computer communications and now domi nates PC peripheral design and support functions It is driver for the operating system The device s firmware just a matter of time before parallel serial ports will be ensures data packet transfer between the device and host phased out entirely But it would be a shame to give up in the USB protocol format On the other hand the the ease and fun of parallel series control alto gether In this article I ll demonstrate a simple way mcm to convert a USB port into a parallel port see Dco MEE Bo Photo 1 Now you can revive all your favorite Sa sd printer port control projects As a bonus I ll describe a method for changing a USB port into a serial port M interrupt from host INTERFACING The fact that USB interfaces are plug and play wins popularity among end users You can Move ete E trol t PORTB plug in or disconnect a USB device any time so PORTD ead le pas rom nor l it s user friendly Unfortunately for developers E implementing USB into devices is quite the oe to control opposite Unlike the conventional serial parallel com munication modes USB protocols are compli cated In addition to the requirement of writing a host control program you have to develop the Figure 1
15. server The AVR PIC sends commands to the Propeller chip over a high speed SPI to command the Propeller to execute various operations all with a simple API that usually consists of a few lines of code to perform any task Thus the AVR PIC programming is easy and with simple APIs engineers can develop complex and rich media applications Both versions are designed to have Arduino I O header compatibility as much as possible but the AVR version is additional ly 100 software compatible and the Arduino tool can be used to develop software for the AVR version as well as AVRStu dio The PIC version works with MPLab as well as a standalone Arduino like tool chain that relies on a bootloader A complete BASIC programming language for the Chameleon is available Code can be written on a PC with a simple editor compiled and downloaded to the Chameleon The Chameleon also features a break away experimentation protoboard built into the PCB The Chameleon costs 59 95 for the AVR version and 69 95 for the PIC version Nurve Networks LLC www xdamestation com Prototype We add aun to PCBs dm 4 when others just sell it 8 Manu terti erroe we Erin ustusj Pro LO LYE pius alveriehy H ro tedio Cionuliiir Component Production TT p www EzPCB com Email sales ezpeb com www circuitcellar com CIRCUIT CELLAR February 2010 Issue 235 EY w February 2010 Issue 235 DEVELOPMENT
16. 00 e lekctor TT sage 1999 110 issues more than 2 100 articies DVD Elektor 1990 through 1999 This DVD ROM contains the full range of 1990 1999 volumes all 110 issues of Elek tor Electronics magazine PDF The more than 2 100 separate articles have been clas sified chronologically by their dates of publi cation month year but are also listed alphabetically by topic A comprehensive in dex enables you to search the entire DVD The DVD also contains free of charge the entire The Elektor Datasheet Collection 1 5 CD ROM series with the original full datasheets of semiconductors memory ICs microcontrollers and more ISBN 978 0 905705 76 7 111 30 CD ECD 5 The program package consists of eight data banks covering ICs germanium and silicon transistors FETs diodes thyristors triacs and optocouplers A further eleven applications coverthe calculation of for example LED se ries droppers zener diode series resistors voltage regulators and AMVs A colour band decoder is included for determining resistor and inductor values ECD 5 gives instant ac cess to data on more than 69 000 compo nents All databank applications are fully interactive allowing the userto add edit and complete component data This CD ROM is a must have for all electronics enthusiasts ISBN 978 90 5381 159 7 40 20 Elektor is more than just your favorite electronics magazine It s your one stop shop for Elektor B
17. 1 800 957 6867 www DesignNotes com PIC SERVO MOTION CONTROL BRUSH BRUSHLESS AND STEPPER MOTORS e controller chips controller boards USB Oscilloscope for 169 50 Logic and Spectrum Analyzers Generator www HobbyLab us Ta Sn ee Ge a on M February 2010 Issue 235 M EN A Aaa A FPGA Embedded Microcontroller Environment February 2010 Issue 235 by John Clayton If you want to set up a simple custom microcontroller development environment this article is for you As you ll see all you need to get started with FPGA based embedded design is a PC some HDL coding synthesis tools and an FPGA board ield programmable arrays FPGAs have become packed with logic gates and many types also include features such as embedded block RAMs hardware multipliers and PLLs Some throw in SERDES memory interfaces or Ethernet MAC functions all the essential items needed for putting together really fancy systems on a chip The FPGA offers these capabilities at an affordable price point which adds excitement for the designer and begs the question How can you take advantage of all that capability Perhaps best of all with FPGAs there is no real penalty for trying out a design If it s faulty you can easily modify it In this sense the FPGA becomes like a quick turnaround personal foundry a veritable playground for experimentation and innovation In this article I ll share some advice on s
18. 1 t gp Power t NBFM Multi channel UHF Transceiver with Programmable RF Power m IA a r k _ mi Radiomett i GM Wie 17 23 VHF Narrow Band VHF Narrow Band VHF NBFM Low Cost FM Multi channel Transceiver FM Multi channel Radio Receiver Multi channel Radio Receiver MURS Modules NEW Gute Sse AH 3L LICENSE FREE BAND v Low Power v Very Long Range 151 820 MHz 151 880 MHz 151 940 MIRAE 154 570 MHz 154 600 MHz VHF Narrow Band VHF 2 Watt Multi channel Transceiver FM 2 Watt Multi channel Transmitter Distributors of Low Power RF modules Zigbee Bluetooth WiFi GPS GSM GPRS LEMOS ace ses sec r INTERNATIONAL sales lemosint com www lemosint com NS JOSUE Using USB for Computer Interfacing Projects February 2010 Wireless Communications RFID Based Liquid Control Part 1 Working with Off the 5helf Components Brian Millier FPGA Embedded Microcontroller Environment John Clayton ae Floating Point for DSP lS RFID Tech Bruce Land Advanced Encryption Standard Understanding AES Without Math Monte Dalrymple n o p o Te ues EEW 5 4 Ail i oe H E il s i 1 cg LH pn SILICON UPDATE A Winning Hand Betting on the ARM Cortex M5 Tom Cantrell TASK MANAGER A ABOVE THE GROUND PLANE Choose Your Own Design Adventure Totally Featureless Clock Part 1 vost IBI WWVB Simulator Fd Nisley NEW PRODUCT NEWS e edited by
19. 128 h082ea166284d924b2765ba2496d8bd125 128 h72f8f66486689816d4a45cccb5d65b692 128 h6c704850fdedb9dabel54657a78d9484 128 h90d8ab008cbcd30af7e4580558b34506 128 hd02cle8fca3f0f02clafbd0301138a80b 128 h3a9111414f67dcea97f2cfcef0b4e673 128 h96ac 422e ad3585e2f93 e81c7 b5df6e 128 h47f11a7114d29c5896fb7620eaal8belb 128 hfcb63e4bc6d279209adbc0Ofe78cdbaf4 128 hlfdda8338807c7 51b112105977808c651T 128 h60517fa919b54a0d2de57a9f93c99cef 128 ha0e03b4dae2af5b0c8ebbb3c83539961 continued on p 57 CIRCUIT CELLAR e WWW circuitcellar com Listing 5 Continued from p 56 different input byte 4 D5DLLLIS endcase case byte 3 0 4 b0000 ibox 4 b0001 TDOX 4 b0010 ibox 4 b0011 ibox 4 b0100 ibox 4 b0101 ibox 4 b0110 ibox 4 b0111 ibox 4 b1000 ibox 4 b1001 ibox 4 b1010 TDOX 4 b1011 ibox 4 b1100 ibox 4 b1101 ibox 4 b1110 ibox default ibox endcase end endfunction msb_ibox 127 120 msb_ibox 119 112 msb_ibox 111 104 msb_ibox 103 96 msb_ibox 95 88 msb_ibox 87 80 msb_ibox 79 72 msb_ibox 71 64 msb_ibox 63 56 msb_ibox 55 48 msb_ibox 47 40 msb_ibox 39 32 msb_ibox 31 24 msb_ibox 23 16 msb_ibox 15 8 msb_ibox 7 0 of understandable logical operations is not feasible This is why a table look up is used The object here is to scram ble the individual bytes before per forming any other operation One rea son why this step is necessary is because ASCII text effec
20. A recent translation of rs232 syscon into VHDL is now available If anyone translates sim syscon into Verilog I d be pleased to receive a copy Also note that in sim syscon the w command write has been renamed as t fill so that the write command can be revamped to handle multiple data items on a single command line This should be a useful modification if you want to use the interface for load ing processor code or large volumes of data to the target system The number of command lines needed can be reduced by more than an order of mag nitude While it is difficult for an FPGA to compete directly with ASICs on funda mental clock speed power per MIPS analog capability or low cost in vol ume of millions of units I like to think they get closer than anything else can at fairly low cost And besides I proba bly won t be selling millions of units any time soon But I should be having fun along the way amp John Clayton morianton gmail com holds a B5EE from Brigham Young University and an M5EE degree from The University of Texas Austin After working for 12 years as a DSP programmer and board designer he is now a principal design engineer at Orbital 5ciences Corporation in Chandler AZ John s technical interests include embedded design FPGAs embedded programming and CNC machining Pus FILES To download the code go to ftp ftp circuitcellar com pub Circuit Cellar 2010 235 ee PNDKR User
21. LVDS types although now that I think of it some FPGAs will support LVDS But there I go digressing again My FPGA breakout board did not contain external RAM Rather than add some I decided to use the internal block RAMs as a rudimentary display buffer Because of the limited amount of memory I ended up with fat 5 x 5 pixel color blocks in a 128 x 96 array supporting eight colors I was able to write a colored rectan gle screen saver program for the RISC PICIGFS84 processor in C and load it via the rs232 syscon module Then I began speed testing the proces sor core I enjoyed watching the screen updates vary in speed as I adjusted the clock all the while keeping an eye on my interrupt serviced LED display which would change at a constant rate because I had a fixed frequency inter rupt request generator set up A fun variation on the full size LCD panel project is to grab an old cell phone and use the FPGA to explore the interface to its little display www circuitcellar com CIRCUIT CELLAR Sometimes cell phone displays can be purchased with datasheets as well WILL ANY BOARD DO The FPGA board used for the coding described in this article was home made and the design files for that board are provided freely to anyone who wish es to use or modify it One day I heard my spouse very clearly utter the non sense word Pondooker and I thought it was a cute name for the board plus it fit into a ne
22. Labs Inc 78 Trace Systems Inc C3 Digi International 45 Intuitive Circuits LLC 75 Mosaic Industries Inc 78 Triangle Research Intl Inc 12 EMAC Inc 75 ronwood Electronics 7 Mouser Electronics 2 3 WlZnet 77 Earth Computer Technologies 11 32 JKmicrosystems Inc C2 NetBurner ATTENTION ADVERTISERS April Issue 237 Deadlines 5pace Close Feb 12 Material Close Feb 22 REVIEW March Issue 256 Theme Robotics Serial Network Hub Part 1 Network Topology and Design Planning Design and Program a Microbot Theme Embedded Programming A Sensor System for Robotics Applications Calibrated Decibel Meter Design RFID Based Liquid Control Part 2 Monitoring System Implementation Bonus Distribution Embedded Systems Conference West PCB East LESSONS FROM THE TRENCHES Putting C Language to the Test Part 1 A Sudoku Puzzle Solving Program FROM THE BENCH Sun Tracker Part 2 Start Tracking SILICON UPDATE Tales from the Crypto A Look at Embedded Design Security Call Peter Wostrel now to reserve your space 800 454 3741 or 978 281 7708 e mail peter smmarketing us zi February 9010 Issue 235 www circuitcellar com CIRCUIT CELLAR Fe ruary 2010 Issue 935 RIORITY 2 INTERRUPT ji by Steve Ciarcia Founder and Editorial Director Feature Creep A marketing guy s worse nightmare is when the engineering team designing his latest product won t stop redesigning the prod uct and just get o
23. advanced mesh networking capabilities an Extension Kit delivers four extra radio boards for 180 Keeping track of all the packets hopping hither and yon isn t easy so the starter kit also comes with a basic version of the Daintree Sensor Network Analyzer SNA wireless network packet sniffer analyzer software see Photo 5 One nice feature is that SNA supports the ever growing list of popular protocols including the aforementioned Zigbee PRO RFACE and 6LowPAN DIAL M3 FOR MOTORS I ve got to admit when the subject is M3 flash MCUS Toshiba isn t the first name that comes to my mind Last I recall they were doing chips based on the MIPS architec ture high end computery ones at that Nevertheless it would be a mistake to ignore a global giant that claims to be Japan s largest semiconductor manufacturer and ranked 3 in the world Electric motors are a huge market and fancy motor drives with sophisticated algorithms are all the rage Toshiba takes on the challenge with the TMPM370 What sets this otherwise conventional 80 MHz 256 KB flash 10 KB SRAM M3 MCU apart is a dedicated Vector Motor Control subsystem that does the heavy lifting Photo 6 The history of silicon has been all about performance But now by virtue green designs and longer battery life or necessity thermal overload low power is where it s at Energy Micro is lead ing the way with 32 bit M5 MCUs that are so cool i e that they could b
24. allow around 6 billion floating point S OURCE operations per second which is enough for serious audio processing and even some video processing Cyclone II FPGA and Quartus II software Altera Corp www altera com www circuitcellar com CIRCUIT CELLAR e February 2010 Issue 235 5 n by Monte Dalrymple Advanced Encryption Standard Understanding AES Without Math Does the Advanced Encryption Standard AES confuse you Try taking the complicated math out of the picture and approaching it from a hardware point of view This will make the encryption decryption process a little clearer and help you ensure your data is protected d always been curious about how data encryption and decryption worked but the math involved had put me off until recently While I was designing a CPU I was asked to add instructions to speed up encryption and decryption using the Advanced Encryption Standard AES which is the current United States government s approved encryption standard This meant digging into the standard and figuring out how it actually works In this article I ll show you how AES really works from a hardware standpoint and hopefully spare you the complicat ed and confusing math that the standard uses to specify the algorithm Instead of terms like affine transformations and Galois Fields I ll describe the algorithm using the Verilog hardware description language and some pseudo code for the high level s
25. an algo rithm close to a binary finite impulse response filter Remember my Circuit Cellar 207 about FIR filters Only the last k bits of the input are used to determine a given bit of the FEC code This value k is the code s constraint length The FEC bits are then inter leaved with the input data bits and sent through the link The simplest solution is to have one FEC bit for each input bit which creates a convolutional coder rate of 1 2 For example the Voyager space mission used a convolutional code with k 7 and a rate of 1 2 but other rates are also possible A rate of 2 3 is possible 2 bits of data 1 bit of FEC to reduce the overhead It s usually achieved with the punctured codes technique simply throw away some FEC bits if the channel isn t too bad Conversely for noisy channels a far ep e BER over Eb No Hamming 7 4 Oo 2 4 6 8 EB No dB higher number of FEC bits is possible For instance the FEC code used for the Cassini probe to Saturn had a rate of 1 6 1 bit of data and 5 bits of FEC code which is enough to drastically increase the signal s redundancy and to cope with unfavorable link budgets The difficult aspect of convolutive codes is at the receiver end The decod ing process is usually made by the use of the Viterbi algorithm This algorithm basically finds the most likely sequence in a chain of hidden states the original bit stream in this case Developed by An
26. and assumes no responsibility or liability of any kind for errors in these programs or schematics or for the consequences of any such errors Furthermore because of possible variation in the quality and condition of materials and workmanship of read er assembled projects Circuit Cellar amp disclaims any responsibility for the safe and proper function of reader assembled projects based upon or from plans descriptions or information published by Circuit Cellar The information provided by Circuit Cellar is for educational purposes Circuit Cellar amp makes no claims or warrants that readers have a right to build things based upon these ideas under patent or other relevant intellectual property law in their jurisdiction or that readers have a right to construct or operate any of the devices described herein under the relevant patent or other intellectual property law of the reader s jurisdiction The reader assumes any risk of infringement liability for constructing or operating such devices Entire contents copyright 2010 by Circuit Cellar Incorporated All rights reserved Circuit Cellar is a registered trademark of Circuit Cellar Inc Reproduction of this publication in whole or in part without written consent from Circuit Cellar Inc is prohibited FCC Part 90 Compliant Modules manufactured by 1 RADIOMETRIX v High Performance v Serial Interface 1j SKI geni 2 25k HEP A Dual Tt Tio aul Cham a aa ee CE 3 ACRI Y
27. and decoding in particular With this information you ll be knowledgeable enough to use FEC algorithms in a future project elcome back to The Darker Side As humans we are really lucky our brains are quite powerful Aren t you convinced You can make sense of a sentence even if words and letters are missing or incorrect For example I m sure you can decipher this sentence despite its various errors I amm shure yu underztand htis sentince despiite itts varius erors Similarly you can understand a speech even if it s given in a noisy environment The reason Simply that our language has an intrinsic high level of redundancy and our brains are pro grammed to use this redundancy and recover erroneous messages In a similar way digital data transmissions and especially wireless links wouldn t be usable without error correction mechanisms Unfortu nately noise and interference add errors to most Gaussian noise 1 Vnus communications There are two usual methods for avoiding errors or more exactly for living with errors The first method is to add an error detection system i e a checksum The receiving device can then check if the message is error free If it isn t it can ask the sender for a retransmis sion This is a good solution but it may not be usable if there are a lot of errors through the transmission channel For example let s say your messages are 50 bytes long 400 bits If you get
28. axis If the shadow falls on a sensor it will output less voltage The control pro gram will attempt to keep all sensors at their peak output by moving the sensor module about its present position m N The sensor module is located on a motorized X Y platform One motor will move the sensor module up and down from horizon to directly overhead and a second motor will move it left and right rotating along the horizon The sensor module s changing output can simplify movement calculations if its sensors are aligned with the X Y axis of movement With this approach any change in the two sensors along the movement axis affects only that axis Two sensors on an axis are required for samples to give real time differential position changes along that axis The motors used to pan and tilt are actually servomotors The pan servomo tor is externally geared to rotate the sen sor module 360 The tilt servomotor directly drives the sensor module s tilt from horizon to horizon through the maximum azimuth Servomotors are position oriented devices The control signal you provide identifies where within its total range of movement you want it to be The servo then drives the motor to move toward that point and keep it there The servo control signal is PWM with a minimum repetition rate of 20 ms The on portion of the signal must vary from 1 25 ms minimum position to 1 75 ms maximum position The total movement range ther
29. because VHDL is strongly typed I believe that Verilog is more appropriate for the easygoing experimenter If translation is to be performed from one language to the other I recommend doing it the old fashioned way by hand I don t currently know of any really good automated free tools for the purpose DESIGNERS COME FIRST One principle that I think is selt evident but which is quite often sacrificed in industry for the sake of cost reduc tion or basic economy is this The designer developer is a respectable person and some effort should be expended to make life easier for that person Now back in the good old times Like the late 1970s there were these simple moni tor programs that developers used on SBCs They were extremely low level programs like Motorola s MIKBUG or the firmware for Steve Ciarcia s Z 80 Applications Proces sor ZAP These monitor programs filled a very important function by providing the ability to reset read modify write and single step or begin code execution at a given CIRCUIT CELLAR e www circuitcellar com Developing module or function under test Figure 1 A module under test can be run through its paces using the actual target FPGA instead of a simulator This is the concept used point Now within an FPGA you can create state machines that provide many of these basic functions in hard ware without making any demands on the target processor at a
30. bridge the workbench gap It s tuned to resonance with a parallel capacitor installed as C15 on the circuit board Pick the capacitor value by measuring the transmitter s antenna coil induc tance then plugging that value into this formula l C15 21 60 x 10 Loon A tank parallel LC circuit has a high impedance at its resonant frequency so you can measure the antenna current using R17 as a sampling resistor 50 087 2 STOP AVC1 2 144 V Figure 5 The modulator output runs 10 dB below full power during the PWM pulse that ends when the output bit goes low CIRCUIT CELLAR www circuitcellar com then turn on your test equipment to find the culprit You also can couple the output sig nal directly to the receiver s ferrite bar antenna by wrapping a few turns of wire around the bar In this case R17 provides the LM386 s minimum allowed load resistance and dissipates essentially all the output power In either case the receiver will almost certainly overload and misbe have unless you dramatically increase R17 to reduce the power output There s no algorithmic way to predict the correct value of R17 so start high and decrease the resistance until your receiver just barely works That will also ensure you re not forcing bogus time codes into your neighbor s receiver Remember that LCD monitors oscilloscopes and other common gadgets may produce enough EMI at or near
31. converter circuit Michael Chan keensd hotmail com graduated in 1980 with an MSEE He teaches Mathematics and Computer Technology Robotics at Albert Campbell Collegiate Institute in Toronto Michael s interests include developing electronic projects computer interfaces games and programming Descriptions of his recent work are available at www keendesigns webs com EFERENCES S Allman The HID Class EDN 2002 J Axelson USB Complete Lakeview Research 2005 D Lichtel Implementing a USB equipment Interface Using the Microchip PIC16C745 QEX May June 2004 OURCES HIDComm ActiveX and PIC18F4550 Microcontroller Microchip Technology Inc www microchip com WWW circuitcellar com CIRCUIT CELLAR DONUS O February 2010 Issue 235 CIRCUIT CELLAR DIGITAL PLUS BONUS
32. have a Q around 10 where Q would have a bandwidth of 6 Hz transmitter frequency is fixed WWVB is the ratio of center frequency to The receiver board specifications defines 60 kHz that bandwidth d Touch panel amp Touch controller AMD Geode LX800 500MHz 512M DDR RAM 4G FLASH HDD SD card support Windows XP embedded A N j Ca E Windows XP based Touch Controller USB ETHERNET RS232 RS485 port Windows 2000 XP Linux support accommodates the crystal filter s tol CHEN erances Therefore you cannot assume a passband centered at 60 000 kHz A 59 925 kHz carrier could well lie in the filter s stopband where the attenuation should exceed 50 dB Simply turning up the transmitter power might punch through the fil ter s attenuation but getting the car rier on the right frequency seemed to be a better solution My parts heap included a bag of 12 MHz microprocessor clock crystals with a frequency of exactly 200 x 60 kHz The Pierce topology logic gate oscillator in Figure 1 produces a 12 MHz clock signal to drive the 74HC40103 count er which divides it down to 120 kHz The 74HC109 flipflop then produces a precise 60 kHz square wave Unfortunately the crystals lack documentation and I lack the ability to measure their parameters The gt SD CARD support correct values of C1 and C2 depend gt RS232 x 2 ports gt USB pot D on the properties of both the cryst
33. helping thousands of engineers around the world Leonard Weber You can t beat an LPKF system for prototyping We do up to i Agilent take their development time from days and weeks to minutes and hours In today s race to market it s like having a time machine i Mn OA D Y45 www lpkfusa com pcb OJ UND 1 800 345 LPKF Laser amp Electronics ay A data from devices such as pedome ters and heart rate monitors Sensors in the kit include an integrated three axis accelerometer an altimeter along with temperature and battery voltage sensors Also included is a large 96 seqment LCD The Chronos includes a USB RF access point for wireless set up and PC connectivity as well as multiple production ready open source proj ects to foster easy evaluation design and community collaboration The kit is available in three different RF frequency bands 915 868 and 455 MHz allowing for worldwide usage II s Simplicill and BM Innova tions s BlueRobin RF protocols enable developers to easily establish wire less links regardless of their RF Knowledge right out of the box The new e2450 Chronos costs 49 Texas Instruments Inc www ti com CIRCUIT CELLAR www circuitcellar com Challenge yourself against other top embedded engineers around the world in DesignStellaris 2010 sponsored by Texas Instruments Use the Stellaris LM3S9B96 microcontroller from Texas Instruments with Keil s Re
34. history puted by Matlab in blue and the actu xl nl lt xln al response of the FPGA implemented e c xl s next state filter in red The red points follow the e 25 ade exact solution fairly well but diverge end a little at low frequency 9 It b di Matlab RU t became tedious to use Matlab to audio_out_FP lt f_coeff_x_value generate the filter coefficients con next state vert the coefficients into custom ad a cO Dn floating format and then write the 15 Verilog So I wrote a Matlab script to begin t the filt ficat oN wait for the audio clock and one shot it convert the filter specification to Ver if lr clk amp amp last clk 1 ilog given the order of the filter the begin state lt 4 dl filter type Butterworth etc and the io ene S qu aue cutoff frequencies The script uses a end Matlab signal processing toolbox i ae E p m i else if Ir_c ast clke function t f2s0s to convert the fil begin ter to SOSs The Matlab script output last cik lt 1 hl for a fourth order filter is shown in ang eM Listing 2 as Verilog source The As erui and Bs and gain are the SOS filter begin constants see Listing 2 default state is end state State lt 4 d15 The IIr4sos module is a state and endcase machine running at about 27 MHz that sequentially performs all the sd floating point filter operations in less endmodule than 2 us which is easily fast enough to keep up with a 48 kHz audio sample end
35. s monthly electronic 4 newsletter News Notes will keep you SN y up to date on Circuit Cellar happenings Stay in the loop Register now It s fast It s free www circuitcellar com newsletter CIRCUIT CELLAR www circuitcellar com the picture that s worth the thousand words it would take to describe all the on chip goodies When it comes to performance clock rate is usually all anyone talks about and the 3U is no slouch running at up to 96 MHz But when dealing with so much I O the ability to move data around quickly with minimal CPU overhead e g driver software and stalls due to bus contention is just as important Featuring a five layer bus matrix dual peripheral bus distributed RAM buffers and 22 channel DMAC the 8U keeps the traffic moving even at the peak of rush hour Proving the 3U is no fluke Atmel has just announced their second line of M3 parts the SAMS3S I haven t seen the datasheet yet but according to the press release the 3S has some interesting features on die termina tion resistors low speed not just active and sleep power optimization PIO DMA memory ECC and back ground CRC encrypted external bus and enhanced peripherals In the marketing pitches migrat ing from ARM7 to M3 is treated as an easy pushbutton affair But actual ly there are under the hood differ ences with things like interrupts power management and I O drivers To ease the migrat
36. short stretch of trace on either side of the PCB You must run a piece of wire along the top trace down through the hole along the bottom trace of the board and finally solder it to the traces on both sides In the layout process this can mean some special planning to make sure that you not only leave enough trace next to each feed through hole via but also beef up the trace width to and from the hole You may also want to increase the via size to match components Drilling tiny holes by hand becomes somewhat easier by using a Dremel tool and drill press frame Miss registration between layers top and bottom may make it impossible to work with hole sizes smaller than 0 030 68 or 69 drill Early PCBs were single sided Through hole component con nections were made on only one side and required a lot of room for the circuit traces The copper traces on a PCB elimi nated the time consuming job of hand soldering wires to phys ically connect components as was done in the past Can you say vacuum tube The ability to plate the inside of through holes with copper opened the door to double sided PCBs and eventually multi layer more than two PCBs For us do it yourselfers double sided PCBs are about as complex as we can get and we must put up with having to solder a wire in each via There are some systems that use tiny rivets that you swage into each hole But this process seems to be more hassle than it s worth The PC
37. the output is zero because the input is less than one Oth erwise shift the floating mantissa to the right by 0h89 floating exponent to form the absolute value of the output 4 pole Butterworth cutoffs at 2400 and 4800 Hz log filter output amplitude x Ct measured log frequency Figure 2 Computed and observed filter response The line is the exact response The points are the observed floating point filter response on the FPGA PN Qo integer Form the 2 s complement signed integer I coded the above outlines into Ver ilog for conversion to hardware on the FPGA I wanted to see how fast I could make purely combinatorial floating point execute so there is no pipelining or clocking of the arithmetic modules Remember that every statement in Ver ilog represents the signal on a wire or bus and therefore every statement can change value simultaneously The code for the floating multiplier is shown in Listing 1 The low level unsigned integer multiply of the man tissas is performed by a small module which gives the Altera Quartus II soft ware a hint that a hardware multiplier should be used The 9 bit x 9 bit multiply yields 18 bits of which nine are selected for output in the asynchronous always Q statement All of the modules are available on both the Circuit Cellar FTP and the ECE5760 course website The Quartus II design software converted this multiplier code to about 60 logic ele men
38. the problem wasn t immedi ately obvious So I recompiled the code this time adding a debug port which would show the shift register contents and finite state machine state This quickly led to the ah ha moment and the problems were fixed in the code Hopefully with the building block provided in this article you will not be CIRCUIT CELLAR e www circuitcellar com constrained to work at such a low level as this But I can t guarantee it and you may need a logic analyzer or even gasp a simulation or two Once the design environment is working many problems can be attacked by looking at register con tents and reasoning about what the unit under test development is actually doing I was able to develop several dif ferent cores by using the rs232 syscon core and these are all posted at www opencores org Some of the older projects will have earlier versions of the support environment which don t include some of the features now present LCD PANEL One of the fun dreams I realized with my completed RISC PIC16F84 core was to hook it up to an old VGA resolution LCD flat panel from a lap top I purchased a broken laptop on the Internet that would only put up error codes on the screen This was what I wanted because I knew I could use the FPGA to scope out the signals present at the LCD interface I made sure it was an older parallel direct drive type of display not one of the newer high speed serial
39. the sensitivity of the device High values boost low lux levels when used in lower light environments while lower values prevent high brightness environments from pre saturating the output LIGHT SENSOR MODULE When experimenting with SMT components it can get expensive to have prototypes made for each revision of a design not to mention the turnaround time to get proto types remade It is extremely helpful to be able to make your own PCBs quickly I don t use this approach for every prototype only small SMT boards because it s nearly impossible to prototype a circuit using these parts without a PCB This project requires four ISL29102s placed quad rant style around a small baffle which acts to shade sen sors when not pointed directly at a light source the sun This small PCB becomes the project s sensor module and is mounted on an X Y servo assembly When pointed directly at a light source each sensor should output an equal value related to the source s www circuitcellar com CIRCUIT CELLAR Direct sunlight Table 1 This chart compares light levels with the circumstances producing them E VDD VOUT module must be moved to correct this alignment error The microcontroller adjusts the X Y servo assembly to keep the module pointed directly at the sun The microcontroller also logs the servo assembly s X Y coordinates to provide data to determine the time of day DRAW PICTURES I use Cadsoft s Eag
40. to PLC 16 Digital Inputs 24VAC or DC l dx hi speed encoders XBE E Socket for ZIGBEE Interface Option ABEE is a reg trademark of Digi International Battery Backed Real Time Clock Call 1 877 874 7527 I2C iw www tri plc com cci htm At prices below most other basic PLCs Ru rs ELECTRONICS C OR PORA TION Electronic and Electro mechanical Devices Parts and Supplies Wall Transformers Alarms Fuses Relays Opto Electronics Knobs Video Accessories Sirens Solder Accessories Motors Heat Sinks Terminal Strips L E D S Displays Fans Solar Cells Buzzers Batteries Magnets Cameras Panel Meters Switches Speakers Peltier Devices and much more www allelectronics com Free 96 page catalog 1 800 826 5432 3 Separate Buses oV amp 3V Simple ASCII Interface Cross Platform All OS www i2cchip com it writes your USB Code Both PC and Peripheral programs understand your data items even odd sized ones and give you convenient variables to handle them Creates complete PC and Peripheral programs that talk to each other over USB Ready to compile and run Large data Reports 64 000 bytes sec per Interface PICBASIC Pro Easily creates devices with multiple MPASM C18 Hi Tech C Inte rt ltiple Identities nterfaces even multiple Identities PICBASIC Pro Automatically does MULTITASKING PIC TE qoos Makes standard or special USB HID MPASM H
41. with 200 000 bit samples Quite close I coded a small SciLab simulation of this system The code is available on the Circuit Cellar FTP site The good news is that the simulation follows the theory Figure 4 shows a comparison of the theoretical bit error rate with vary ing noise level and the results of my simulation for 200 000 bits transmitted Quite nice isn t it Just take care because the horizontal scale isn t noise voltage It s a value called E N which is defined as the energy per bit to noise power spectral density ratio It s basically the signal to noise ratio SNR in terms of power not voltage normalized for 1 bit trans mitted In the current example as you are using NRZ modulation 1 bit is transmitted for each hertz of bandwidth Thus E N and SNR are identical but I prefer to use the unit in the literature for more complex examples So E N O db means noise power equals signal power the same RMS voltage E N 6 dB means noise power 6 dB lower than the signal four times lower as 109 19 3 98 so the RMS voltage is two times lower than the signal voltage as a volt age is proportional to the square root of the power Remember U v P x R THE NYQUIST LIMIT Let s cover a bit more theory before experimenting with FEC codes Claude Shannon 1916 2001 is probably the father of information theory One of his well known results published shortly after World War II is the Shan no
42. 00 SpYder Discovery Kit maida em The SpYder Discovery kit from Freescale valued at rye ecrit a 16 00 comprises a USB programmer debugger BDM Eok S a CD ROM with a special version of CodeWarrior and one MCS9S08 8 pin PDIP microcontroller Cheaper than 11 issues from the newsstand Save 57 of the cover price of 92 45 O omamme o e a m am m a 108 45 ji pee Elektor ye zx om ctm m a a msi im i mm our saving Offer available in US and Canada only Please allow four weeks delivery time Take out your subscription now ektor www elektor com cc Phone 860 875 2199 TL lk LEILELILLIL LII C1 f ttt Pt I LLILEP 12 LLLI LLL LL PEP TTT tt ef LLLI tt tt PTT tT C1 Down Across 1 Shoren 3 Curie temperature 2 PCB s legend Hint white and yellow 5 Smaller than a notebook 4 Classic jump 6 Frank Wanlass 1967 patent f 1 000 000 bits 8 299 792458 V 9 PC off 10 x 10 Protective pipe for wiring 13 Fab 11 Operation time two words 16 PGDN two words 12 Conductance S 18 Combines signals 14 Component list 19 Mainboard 15 Compare to a standard 20 12 39 17 Ebs The answers are available at www circuitcellar com crossword A February 2010 Issue 235 m THE DIRECTORY OF AD FORMAT Advertisers must furnish digital files that meet our specifications www circuitcellar com advertise ALL TEXT AN
43. 1 work 4 1 end end keyexpand the sbox function to each of the 4 bytes Then one or more bits are inverted using the constants shown in Listing 8 The final step adds a word from the previous iteration creating the least significant word of the new round key The remaining three words of the new round key start with this word succes sively adding words from the previous iteration to create the full round key You ll notice that each cipher key is expanded to a specific set of round keys I haven t gone through the details but I presume the round keys are even ly distributed over all possible values I suspect that this is the reason for the inclusion of the byte shift and inversion of different bits for each round Like the encryption decryption Ver ilog module the key expansion module does one step per clock cycle requiring 40 clocks to generate the full set of Listing 8 The key expansion toggles one or more bits during each round This seems to have been included to prevent cyclic patterns from appearing in the round key 0x00000001 0x00000002 0x00000004 0x00000008 0x00000010 0x00000020 0x00000040 0x00000080 0x0000001b 0x00000030 roundCon 0 roundCon 1 roundCon 2 roundCon 3 roundCon 4 roundCon 5 roundCon 6 roundCon 7 roundCon 8 roundCon 9 www circuitcellarcom gt CIRCUIT CELLAR round keys You ll notice that with this implementation the key generation and encrypt oper
44. 60 kHz to swamp the receiv er Try to get good reception at night CONTACT RELEASE The source code for this column sets up the Arduino microcontroller as a WWVB simulator but without much of a user interface The DIP switches at the top of Photo 1 set vari ous debugging modes and the program dumps the current time and interest ing events over the USB serial link The row of empty holes on the cir cuit board to the right of the power supply can connect to an ordinary 44780 based LCD panel The program doesn t use that hardware The schematics shown here do not include the Arduino interface and power supply You can download the complete schematics and PCB layout from the Circuit Cellar FTP site In short use the source al Ed Nisley is an EE and author in Poughkeepsie NY Contact him at ed nisley ieee org with Circuit Cellar in the subject to avoid spar filters Doc FILES To download schematics a PCB layout and Arduino programs go to ftp ftp circuitcellar com pub Circuit_Cellar 2010 235 m R Cerda Pierce Gate Oscillator Crystal Load Calculation Crystek Crys tals Corp 2004 www crystekcrystals com crystal appnotes PierceGate LoadCap pdf Lownoise Productions Parody of WWV Time Station Programming www lownoiserecords com wwv_the_tick html S Nickels Time Server Design Synchronize with the WWVB Time Code Signal Circuit Cellar 220 2008 J Walker Calendar Converter and Inform
45. 981169d98e949b1le87e9ce5528dF 128 h8cal1890dbfe6426841992d0fb054bb16 endcase case byte 3 0 4 b0000 sbox 4 b0001 sbox 4 b0010 sbox 4 b0011 sbox 4 b0100 sbox 4 b0101 SDOX 4 b0110 sbox 4 b0111 Spox 4 b1000 sbox 4 b1001 sbo ox 4 b1010 sbox 4 b1011 SDOX 4 b1100 sbox 4 b1101 S DOX 4 b1110 SDOX default sbox endcase end endfunction msb_sbox 127 120 msb_sbox 119 112 msb_sbox 111 104 msb_sbox 103 96 msb sbox 95 88 msb sbox 87 80 msb_sbox 79 72 msb_sbox 71 64 msb sbox 63 56 msb_sbox 55 48 msb_sbox 47 40 msb_sbox 39 32 msb_sbox 31 24 msb_sbox 23 16 msb_sbox 15 8 msb_sbox 7 0 Listing 5 The inverse of the byte substitution is specified in exactly the same way and requires about the same amount of logic x xkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkxkxxk aes Inverse SDOX T EK KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK function 7 0 ibox input 7 0 byte reg 127 0 msb ibox begin case byte 7 4 4 b0000 msb ibox 4 b0001 4 b0010 4 b0011 4 b0100 4 b0101 4 b0110 4 b0111 4 b1000 4 b1001 4 b1010 4 b1011 4 b1100 4 b1101 AY pL LO msb ibox msb ibox msb ibox msb ibox msb 1ibox msb ibox msb ibox msb ibox msb 1ibox msb 1ibox msb i1ibox msb ibox msb ibox msb ibox 128 h52096ad53036a538bf40a396e81f3d7fb 128 h7ce339829b2fff87348e4344c4dee9cb 128 h547b9432a6c2233dee4c950b42fac34e
46. B layout package lets you choose the number of lay ers you want to use in your project This will be a double sided PCB so interconnecting traces can be placed on the top and bottom layers I ve located the SMT sensors on one side of the PCB and the through hole parts on the opposite side Now each elastic connection between component pins pads can be replaced with a fixed trace along the various PCB layers I like to use as wide a trace as possible especially for power and ground so I usually begin with those nets Although I have m Photo 2 lf you first print out a 1 1 copy of the PCB masks you can save TTS material by taping a small piece directly over the masks and passing the sheet back through the printer to get the mask printed directly on the TT5 traces and spaces trace to trace spacing on this project as small as 10 mils thou sandths of an inch I had no problem with these disappearing during the etch ing process With the PCB layout process complete the application can produce the necessary Gerber plot files that any board house would use to reproduce this project Instead of sending these on to be manu factured you can use the files to begin the DIY PCB process THE FAB The last time I explained this process was in a 1992 article titled Approach ing PCB Nirvana Circuit Cellar 28 The process has changed slightly with improved results but it is still based on masking off areas on a
47. C2OUT ANA RA5S OSC2 CLKO RAG OSCI CLKI RA7 INTO FLTO SDI SDA AN12 RHBO INTT SCK SCL AN10 RB1 INT2 VMO AN8 RB2 CCP2 VPO ANS RB3 KBIO CSSP AN11 RB4 KBI1 PGM RB5S KBl2 PGC RB6 KBIS PGD RB7 T1OSO T13CKI RCO T1OSI CCPZ UOE RC1 CCP1 P1A RC2 VUSB D VM RC4 D VP RC5 TX CK RC6 RX DT SDO RC7 SPPO RDO SPP RD1 SPP2 RD2 SPP3 RD3 SPP4 RD4 PiB SPP5 RD5 P1C SPPe RD6 P1D SPP7 RD7 CK1SPP ANS REO CK2SPP AN6 RE 1 OESPP AN7 RE2 MCLR VPP RE3 PIC18F4550 Figure 2 This is the schematic circuit diagram for the USB Parallel Port Converter firmware logic for my USB interface Most HID classes so simple that you can test the circuit on protoboard as deal with either input devices e g keyboards and mice I did or output devices e g audio video instrument whereas The circuit is externally powered and regulated to 5 V a typical parallel port involves both inputs and outputs through a voltage regulator The 20 MHz crystal pro Therefore in my converter the HID routine must be vides clocking signals to the processor With the help of modified see Listing 2 the microprocessor communications are then initiated between the host via the USB port and the controlled CONVERTER CIRCUIT device via the simulated printer port DB25 terminals As you can see in Figure 2 the converter module does Resistance between the processor terminals and the not require many electronic parts Indeed the circuit is DB25 jumpers are not cr
48. Corp www thatcorp com bod CIRCUIT CELLAR www circuitcellar com ADVANCED FAMILY OF ZIGBEE MODULES The ETRAS series is a third generation of advanced ZigBee module and the first module family on the market to feature the EM557 and EM551 the latest ARM Cortex M 5 SoCs from Ember ETRAS series modules have a footprint of just 19 mm x 25 mm for both standard and PAVLHA versions which repre sents a 40 reduction in size compared to the ETRA2 mod ule They are available with either an on board antenna or a Hirose U FL connector for an external antenna A link budget of 105 dB on the standard ETRAS module gives excellent performance and RF power can be further boosted by the ETRAS LR which adds an extra LNA PA boosting the link budget to 125 dB The ETRAS series mod ules integrate a 2 4 GHz IEEE 802 15 4 compliant transceiv er with up to 192 KB of flash memory 12 KB of RAM and many advanced peripherals To maintain the strict timing requirements imposed by the ZigBee and IEEE 802 15 4 2005 standards the EM557and EM551 integrate a number of MAC functions into the hardware handling automatic ACK transmission and reception automatic back off delay clear channel assessment for transmission and the automatic filtering of received packets ETRAS series modules work from a 2 1 to 5 6 V supply and active power consumption is reduced by over 20 compared to the ETR 2 In deep sleep mode current consumption is reduced
49. D OTHER ELEMENTS MUST FIT WITHIN A 2 x 3 FORMAT E mail adcopy circuitcellar com with your file or send it to IDEA BOX Circuit Cellar PO Box 180 Vernon CT 06066 For current rates deadlines and more information contact Peter Wostrel at 800 454 3741 978 281 7708 or peter smmarketing us Adapt9S12 Modular Prototyping System For education amp development Assembler BASIC C or Forth Supports 9S12A B C D E N X x Robotics Mechatronics amp Automotive Apps Ca freescale GHz Bandwidth Soc Y ak tor Ds sin BGP Industry ys Smallest F Pitch 0 3mm to 1 27 nine BGA UEN WIE Bandwidth to 40 GHz Four different lid options Optional 500 000 insertions Heatsinking to Ironwood ER Y ELECTRONICS www ironwoodelectronics com WWw circuitcellarcom CIRCUIT CELLAR Weather Instruments for PCs electr nica www aagelectronica com Revolutionary new expandlO USB chip A D lt SPI 2C deal for adding USB to sensors amp peripherals No drivers needed for Windows Mac Linux No microcontroller programming required Also check out our USB 232 USB to UART www hexwax com Buy from Mouser amp Farnell Amazing PIC programmer Most devices supported ICSP SOTP amp copy limits t Digike TEX P ped www flexipanel com Actual size patents pending 000 basic overlay board BOB 4 Low cost video data overlay module Features Automatic tex
50. DEDDEVELOPER T EvacoaeaDeveyorene FIND COMPARE BUY y AY ig The Sites for Engineers with a Job to Do with a Job to Do Listing 4 These basic functions are used in the MixColumn operation Each operates on one byte mixing the bits of a byte in unique ways KR KRKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKE aes functions for mixcolumn and inverse KR KRKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKE function 7 0 mul 025 input 7 0 byte begin mul 02 byte 6 byte 5 byte 4 byte 3 byte 2 byte 1 DyUteL DyTeL byte 0 byteLl7 byte 7 7 end endfunction function 7 0 mul 03 input 7 0 byte begin mul 03 bytel6 byte 7 byte 5 byte 6 byte 4 byte 5 byte 3 byte 7 byte 4 byte 2 byte 7 byte 3 byte 1 byte 2 byte 0 byte 7 byte 11 byte 7 byte 0 end endfunction function 7 0 mul 09 input 7 0 byte begin mul 09 byte 4 byteL7 byte 3 byte 7 byte 6 byte 2 byte 7 byte 6 byte 5 byte 1 byte 6 byte 5 byte 4 byte 0 byte 7 byte 5 byte 3 byte 7 byte 6 byte 2 byte 6 byte 5 byte 1 byte 5 byte 0 end endfunction function 7 0 mul Obs input 7 0 byte begin mul Ob f byte 4 byte 6 byte 3 bytel 7 byte 2 byte 7 byte 1 byte 6 byteLO byte 5 byte 7 by
51. EASILY CUSTOMIZED ANTENNAS FROM WHIPS TO CHIPS 159 Ort Lane Merlin OR 97532 9r TECHNOLOGIES linxtechnologies com www circuitcellar com CIRCUIT CELLAR now we ve done it again with Linux The OmniFlash controller comes preloaded with Linux and our development kit includes all tools you need to get your project up and running fast Out of the box kernel support for USB mass storage and 802 11b wireless along with a fully integrated Clock Calendar puts the OmniFlash ahead of the competition Call 530 297 6073 Email sales jkmicro com www jkmicro com JK microsystems Inc MADE IM USA International Orders Welcome E February 2010 Issue 235 February 2010 Issue 235 LOW COST WIRED AND WIRELESS NETWORKING MODULES Rabbit has expanded its MiniCore series of easy to use ultra compact low profile low cost networking modules Available in pin compatible wired and Wi Fi versions the family now includes the Ethernet RCM5760 and Wi Fi RCMS650W The new mod ules offer increased memory for data intensive applications such as building automation and security applications The prod ucts also allow a customer to wirelessly update firmware from anywhere an Internet connection is available to reduce mainte nance costs The MiniCore family provides a rich embedded feature set on an ultra compact mini PCI Express form factor Its small size makes it easy for customers to place wired or wireless network c
52. ENVIRONMENT INA SPORTS WATCH Representing a new era in development Texas Instruments has announced the e2450 Chronos the world s first customiz able development environment within a sports watch Taking the popular line of e2450 development tools to the next level the kit allows developers to easily harness the capabilities of the CC450 microcontroller The Chronos is designed to provide customers with all of the hardware and software needed to immediately begin development of wireless networking applica tions regardless of programming expertise The kit is equipped with sensors for measurement and motion based control and can serve as a central hub for nearby wireless sensors so that users have remote access to real time Why not try a different approach before you head to lunch 1 03 PM Your second board is m ready to test 5 a ig Ms AV Your first board is ready to test d 2 4 EF Your circuit designis EN AE i sieh done and you re ready ff S i LLLI J T Eidem re 3 PM f Your finished board is ready to go j Nice work You just shaved weeks off your development schedule All in a day s work ProtoMat Benchtop PCB Prototyping Machine What would your day look like tomorrow if you could cut yourself free from the board house and produce true industrial quality PCBs right at your desk three iterations of a design LPKF s ProtoMat benchtop prototyping systems are within a day
53. Here you see the firmware logic for the PIC18F4550 used in the USB device s embedded firmware and also a device Parallel Port Converter www circuitcellar com CIRCUIT CELLAR BONUS February 2010 Issue 235 CIRCUIT CELLAR DIGITAL PLUS BONUS device driver creates a dataflow framework for the device to communicate with the host system This is enough to stop many designers from using the USB in their projects MCUs The point of this article is to explain how to convert a USB device with the least amount of hardware into a parallel port controller But I ll also try to make the complexity of firmware and driver writing transparent On the hardware side Microchip Technology program mable USB dedicated microcontrollers open the door to versatile USB control applications The Microchip Tech nology PIC18F2550 18F4550 single chip processor emu lates a USB interface provides more than 20 I O pins and surprisingly requires only a handful of support com ponents On the software side you don t have to start from scratch with firmware development There are adaptable standard firmware sets for ready to use processors It is just a matter of modifying these sets to suit particular applications A convenient way to avoid having to write your own USB device driver is to use a human interface device HID class In Windows there is a comprehensive library of HIDs that define sets of structured I O configura tions Keyboar
54. IYI ITE YyXYyOGgad ga dd qd2p0pWd 4 d gg IIIT II 77 Tl 9 Sl Gl Wl T2 152 92 Ma If either is zero zero MSB of mantissa then output is zero If el e2 lt 129 the result is zero underflow FIITGEII TIT LILII LLLI IT III AI aA ATTA AIT TATA T module fpmult fout fl f2 input 17 0 fl f2 the two floating inputs output 17 0 fout the floating product wire 17 0 fout reg sout the output sign reg 8 0 mout the output mantissa reg 8 0 eout the output exponent extended to 9 bits for overflow wire sl s2 the two input signs wire 8 0 ml m2 the two input mantissas wire 8 0 el e2 sum_el_e2 extend to 9 bits to avoid overflow wire 17 0 mult out raw multiplier output parse fl assign sl f1 17 sign assign el 1 bO f1 16 9 exponent extended one bit assign ml f1 8 0 mantissa parse f2 assign s2 f2 17 assign e2 1 b0 f2 16 9 assign m2 f2 8 0 first step in mult is to add extended exponents assign sum_el_e2 el e2 build output raw integer multiply unsigned_mult mm mult_out ml m2 assemble output bits assign fout sout eout 7 0 mout always begin if either is denormed or exponents are too small the the output is zero if Cm1L8J 1 dd m2 8 1 d0 sum el e2 lt 9 h82 begin mout 0 eout 0 SOUL UF 77 OUTPUT Sign end else both inputs are nonzero and
55. JYXY Y gTPTPIJIXYXITXTYIVIXGHI2YNYYTIYIJJKJIMHIXGHddd f Second order IIR filter M M MMIMMMIMIEIEIMPMMJI LM VIET ITITICITIA LITT ETI TIAA IIIT ISAT IT IITA IA IIIT AT I aT TIS module IIR2sos_18bit_fp audio out audio in b11 b12 b13 al2 al3 gain state clk lr clk reset The filter is a Direct Form II Transposed but is factored into two second order filters and a gain a 1 y n b 1 x n b 2 x n 1 b nb 1 x n nb a 2 y n 1 a na 1 y n na If a 1 is not equal to 1 FILTER normalizes the filter coefficients by a 1 one audio sample 16 bit 2 s complement output wire signed 15 0 audio out one audio sample 16 bit 2 s complement input wire signed 15 0 audio in 7 filter coefficients input wire 17 0 b11 b12 b13 a12 al3 gain input wire state_clk lr clk reset filter vars 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 11 1 111 wire 17 0 f_mac_new f_coeff_x_value reg 17 0 f_coeff f_mac_old f_value input to filters reg 17 0 x1 n input history x n 1 x n 2 reg 17 0 xl nl xl nZ output history y_n is the new filter output BUT it is immediately stored in fl y nl for the next loop through the filter state machine reg 17 0 fly nl fly n2 i o conversion int output of FP calc wire 9 0 audio out int reg 17 0 audio out FP wire 17 0 audio_in_FP
56. John Gorsky THE DARKER SIDE Living with Errors CROSSWORD 4 4 An Introduction to Forward Error Correction Robert Lacoste INDEX OF ADVERTISERS 4 256 Preview FROM THE BENCH Sun Tracker Part 1 PRIORITY INTERRUPT SO Create a Direcional Habt S568050 Pesce Cecep Jeff Bachiochi 5teve Ciarcia OQ February 2010 Issue 235 CIRCUIT CELLAR The New High Performance Catalog Industry s only full featured online catalog Browse Search eCheck Stock Buy Paare ocatueg Brewis Prensa icy Jan DOS Catalog 40 d Si The Newest Products Sd For Your Newest Designs OVER A MIELI PRODUCTS ONLINE NEW CATALOG every 80 oars oven 380 Leaning SUPPLIERS ALPE Amph OS EET A mm n NR iud nn teary E E Gp ED ED GS EB EJ E d E Ed ED GR E UD OE Hl Try It Now at www mouser com WARNING Designing with Hot New Products May Cause A Time to Market Advantage Introducing the new enhanced high tech online catalog Allowing you to browse search check stock buy and more An industry rst And only online N catalog to offer all these features without ever having to leave the catalog L a tti company www mouser com 800 346 6873 Mouser and Mouser Electronics are registered trademarks of Mouser Electronics Inc Other products logos and company names mentioned herein may be trademarks of their respective owners WIRELESS SENSOR HETWORK DEVELOPMETT TOOL
57. K develop ment boards and ANY9O0O0 USB dongles on an as needed basis ANY DESIGN development kits Part number ANY 900 DK cost approximately 440 Adaptive Network Solutions GmbH www an solutions de COMPACT ANTENNAS WITH SMA CONNECTOR Antenna Factor s HW Series half wave center fed dipole antennas and quar pact low cost antenna solution ter wave monopole antennas are now available with standard SMA connector These antennas attach using an FCC terminations HW Series antennas are ideal for applications requiring a com compliant RP SMA connector or the newly available standard SMA connector Alternate connectors and custom colors are available y Naw HW SERIES DIPOLE ANTENNA for volume OEM orders The antennas are Now Available with Standard SMA Connector available in standard center frequencies of 2 515 418 455 868 and 916 MHz The 868 and 916 MHz versions are half wave center fed dipoles while the 515 418 and 455 MHz versions are all quarter wave monopoles The HW 5eries feature an internal coun terpoise an omnidirectional pattern out standing VSWR and excellent perform ance he antennas are rugged and dam age resistant HW Series antennas cost 4 98 in vol ume quantities Antenna Factor www antennafactor com NEW PRODUCT News Edited by John Gorsky Qo February 2010 Issue 935 CIRCUIT CELLAR www circuitcellar com ULTRA LOW POWER LOW PROFILE COOLER USES PULSES OF AIR
58. Oxc60d Association Status Association successful 0x00 aok Channel Summary PAN ID Ox lff xc60d 00 80 e1 02 00 00 00 26 Ox0000 00 80 e1 02 00 00 00 5a BENHEHEHEE d it ees a c Packet Type z 05 42 41 060 00 80 IEEE 802 15 4 IEEE 802 15 4 ETTA ZigBee RF4CE NUK Data IEEE 802 15 4 Acknowledgment ZigBee RF4CE NUK Data RFACE CERC CERC User control pressed ZigBee RF4CE NUK Data i B Session File Protocol Stack ZigBee RF4CE Devices 2 Frames 685 Command Association es 05 42 41 061 05 42 41 065 05 42 41 067 05 42 41 086 05 42 41 089 05 42 41 107 0x0000 Oxc 60d Oxc 60d 0x0000 For Help press F1 Photo 5 The STM32W Starter Kit includes an evaluation version of the Daintree Sensor Network Analyzer SNA It uses one of the three radios in the 5tarter Kit as a sniffer to capture and decode traffic between the other two 32W is a noteworthy option The chip is as much about the radio as the M3 MCU itself The latter is rather conventional with a typical mix of peripherals and according to the specs the core tops out at 24 MHz which is somewhat less than typical for an M3 Indeed a likely scenario has the core running at just 12 MHz to reduce power because that s the minimum clock rate required by the radio I m no RF expert but features like two point direct syn thesizer modulation and a low IF superheterodyne receiver apparently do the trick whe
59. SET The ANY DESIGN development kit is a new toolset for the development of 868 915 MHz wireless sensor network applications in energy management smart metering industrial and building automation and more The easy to use toolset includes ANY9OO RF mod ules USB dongles development tools and embedded software supporting IEEE 802 15 4 based protocols including ZigBee PRO and OLoW PAN as well as proprietary solutions Combined with Adaptive Network Solutions s RF design and customization services these tools empower OEMs and system integrators to take their new products from concept to market faster and more cost effectively The development kit provides developers with everything they need to create market ready wireless systems and applica tions while mastering the intricacies of WSN technology The kit features support of third party applications and convenient reference drivers as well as APIs for UART I C ADC and 1 wire peripherals The ANY DESIGN kit supports the intuitive development environment from Atmel including an embedded debugging feature using Atmel JTAG in circuit debugger The ANY DESIGN development kit consists of an ANY9OO USB dongle with JTAG programming adapter three fully pro Grammable ANY BRICK boards and a CD ROM containing documentation and software including the Smart MAC Suite soft ware toolchain and network visualization tool The development kit can be extended with additional ANY900 BRIC
60. The 18 bit floating point described here allows up to 70 floating point multipliers and around 150 floating point adders to be placed on an FPGA teach a course at Cornell University in which students learn how to use Verilog and FPGAs to build processors and custom hardware The goal is to build interesting devices such as robots games and lab instruments What distinguishes the projects from general microcontroller proj ects is the high parallel throughput possible using parallel hardware on the FPGA There is a definite need for a light weight floating point format in this class Floating point arithmetic is very handy for designing filters and other image and sound related computations You can concen trate on the algorithm at hand without worrying about fixed point scaling or overflow Numerical dynamic range is hugely increased although algorithm accuracy is always an issue Also numerical tools such as Matlab or Octave pro duce filter design results in floating format so the conver sion of the design results to hardware is easier There are several dozen formats for floating point numbers ranging from the high accuracy 32 bit IEEE 754 standard to lowly 8 bit formats used in speech and video compression and for lecture examples So why would I want to invent anoth er format There are several reasons The basic reason follows from a quote from physicist Richard Feynman What I can not create I do not understand Building f
61. UIT CELLAR Figure 6 This diagram illustrates Hamming FEC encoding and decoding Here the input data set is 1011 and is transmitted with three additional FEC bits Even if one bit was inverted during the transmission the Hamming decoder was able to reconstruct the message Unfortunately Figure 7a is our start ing point with these added bits Then the positive effect of the FEC code must be taken into account It will improve the bit error rate as long as the number of errors is reasonably low The result is provided in Figure 7b What is 010 001 happening For high error rates the FEC code can t really help because there are too many errors Thus the BER is even higher than without any FEC code because of the higher bit rate At a certain point the advantages begin to out weigh the disadvantages and the FEC code provides an improvement in terms of BER With sufficiently low error rates the effect of the FEC code provides asymptoti cally a constant gain in deci bels which can be easily cal culated as R t 1 R is the code s expansion rate Here it s 4 7 t is the number of bit errors that can be corrected Here it s 1 So the theoretical improve ment is 4 7 x 1 1 8 7 1 14 which translates into 10log10 1 14 0 58 dB That s quite low but close to the simu lation isn t it How do you get improved perform ance Use more sophisticated FEC Leading Embedded Development Tools an
62. While donning rubber gloves for protection I held the corner of the PCB within the bowl With my free hand I used a small sponge about the size of a domino to gently wipe the PCB surface with the acid I continued to coat the copper with fresh acid from the bowl by wiping away the oxidizing copper from both sides of the laminate surfaces Eventually I began to start seeing through areas where all the copper had been removed Doing this by hand with Photo 3 Once the TTS mask has been reheated and has bonded to the copper lam inate the TT5 is easily removed by soakinq it in water a sponge gave me better control of the etching process I was able to apply acid to particular areas that were taking longer to etch When I could see clearly through the PCB see Photo 4 and all evidence of haziness thin copper coating had been etched away I washed off any remaining acid on the PCB with clean water and then removed the toner mask with ace tone some nail polish remover The PCB was now ready for trimming drilling and adding components When you do this don t forget to safely dispose of or store the remaining acid ADDING PARTS After drilling the vias and component holes I meticulously applied the small est amount of solder paste to the 24 SMT pads of each light sensor I placed the PCB on a piece of aluminum to bet ter control heat dissipation and then into a toaster oven until the ooze melted and coated the cop
63. YT Ee 1 EE TT EE e MMM Various 32 Bit Possibilities p 30 Floating Point for DSP on an FPGA p 46 Forward Error Correction Explained p 62 CIRCUIT GELLAR THEMAGAZINEFOR COMPUTER APPLICATIONS 235 February 2010 WIRELESS COMMUNICATIONS Multi Functional Wireless Monitoring and Control Build a WWVB Style Signal Transmitter Customize an Embedded MCU Environment The Advanced Encryption Standard Exp laj aed Ili 0 74470 75349 0 5 95 U S 6 95 Canada A SSH ENCRYPTED SERIAL TO ETHERNET SOLUTIONS did Aa ES Device P N SB70LC 100CR 9 5 suk Kit P N NNDK SB7OLC KIT p 2 port serial to Ethernet server Qty 1000 P Device P N SB700 EX 100CR Kit P N NNDK SB700EX KIT SB700EX 129 2 port serial to Ethernet server Qty 1000 with RS 232 amp RS 485 422 support Device P N CB34 EX 100IR Kit P N NNDK CB34EX KIT 149 CB34EX industrial temperature grade Qty 1000 p J 2 port serial to Ethernet server with RS 232 amp RS 485 422 support and terminal block connector Instantly network enable any serial device Works out of the box no programming is required Customize to suit any application with low cost development kit 256 bit encryption protects data from unauthorized monitoring Features 10 100 Ethernet TCP UDP SSH SSL modes DHCP Static IP Support Data rates up to 921 6kbps Web based configuration Need a custom solution NetBurner Seria
64. a niea ILhank D nimini te terirgairs MP3P DIY KIT Do it vou Include Firmware Full source Code Schematic 160 220 qty 100 aty 1 150 qty 100 200 qty 1 180 qty 100 220 qty 1 ic ICbank FED irina a Powerful feature MP3 Encoding Real time decoding 320Kbps Free charge MPLAB C Compiler student edition apply Spectrum Analyzer Application Focusing for evaluation based on PIC Offer full source code schematic Microchip dsPIC33FJ256GP710 16 bit 40MIPs DSC VLSI Solution VS1033 MP3 CODEC NXP UDA1330 Stereo Audio DAC Texas Instrument TPA6110A2 Headphone Amp 150mW 320x240 TFT LCD Touch screen SD SDHC MMC Card External extension port UART SPI I2C 12S Powerful feature Play MP3 Information Reward forward Vol Focusing for MP3 Player SD Card interface Power battery offer full source code schematic Specification MCU Atmel ATmegai28L MP3 Decoder V51002 VS1003 WMA IDE Interface Standard IDE type HDD 2 5 3 5 Power 12V 1 54 LCD 128 x 64 Graphic LCD Etc Firmware download update with AVR ISP connector Powerful feature Play MP3 Information Reward forward Vol Focusing for full MP3 Player Without case IDE Interface Power Adapter Offer full source code schematic www icbank com Listing 3 Verilog description of a second order IIR filter FIRILEPTEEIE EEYYITXTYTYXIMIYIY
65. active roll stabilization dynamic stability control brake fade compensation and dynamic traction control it might as well be a lap at the Indy 500 because could drive up the ramp just like that and get away with it My hat is off to the designers responsible for all this increased functionality and safety and yes I ll keep my overconfidence in check At the same time think BMW pushed the computerized features envelope totally off the deep end with their initial version of iDrive BMW s version of an all in one rotate tilt push control button for all entertainment climate user settings and communica tions functions Don t get me wrong unlike the trade press who think was simply too low tech to learn anything that electronically sophisticated readily use and appreciate its functions My criticism is that BMW did too much innovation in a single model year change without fully determining whether the majority of drivers in the U S at least really wanted all their control functions con centrated in a single knob couldn t help but laugh to myself when thought that there must ve been an iDrive design meeting back in Germany before its release where the one guy in charge finally slammed his riding crop on the desk and yelled They veel learn to use it The irony in making the latest 2010 iDrive acceptable to the trade press is that all the redesigns since 2001 have basi cally been retrogrades adding many of the buttons and indep
66. ages sleep modes clock gating and so on But by virtue of their sin gle minded focus and attention to detail Energy Micro does stretch the concept not to mention battery life further Batteries deliver power but store energy i e power over time and that s what matters Thus a lower power MCU isn t always better if it takes a lot longer to do the work at hand The idea is to sleep a lot then wake up and get work done fast so you can sleep even more But the devil is in the details and all sleep modes aren t created equal Some are quick and easy to wake up from www circuitcellar com CIRCUIT CELLAR while others are more like a coma little more than The Big Sleep mode i e an ON OFF switch To that end the Energy Micro MCUs fea ture four different sleep modes that allow designers to fine tune the trade off between power consumption and responsiveness Energy Micro hoards energy that other MCUs may leave on the table with a Peripheral Reflex System that handles a measure of I O autonomously without having to wake the processor They also pay attention to reducing the power con sumed by the peripherals themselves For instance the ADC can perform 12 bit conversions at up to 1 MHz consuming 200 uA But if you don t need the performance you can cut back the resolution and sample rate to slash power consumption to for exam ple just 500 nA for a 6 bit at 1 kHz application Ther
67. al 4 and the logic gate so the 27 pF I used ES is simply a guesstimate An uncompensated crystal oscillator should have an accuracy around 100 parts per million which means the 10 2 CUWIN3100 gt ARMY 32bit 266MHz WinCE 5 0 Core gt RTC CIRCUIT CELLAR www circuitcellar com divided down carrier frequency should be within 6 Hz of 60 kHz The receiv er s assumed 10 Hz bandwidth could be entirely on the other side of 60 kHz from the oscillator s crystal but it s reasonable to assume that the crystal frequency will be either within the passband or very high up on a skirt However my HP 8591 spectrum analyzer reports the actual oscillator frequency as 12 00664 MHZ about 600 ppm high Working through the instrument s accuracy specifications shows that the measurement error is 2 kHz so the oscillator really is run ning high My HP 54602 oscilloscope reports 11 99 to 12 01 MHz while a hand held frequency counter weighed in at 12 0066 Your results will cer tainly differ I have no confidence that the receiv er s crystal filter has any better accuracy than that its bandwidth is just 10 Hz or the stopband attenuation is 50 dB with steep skirts As it turns out the WWVB receiver has no trouble with a 60 030 kHz carrier so perhaps all of this fussing was for naught The oscillator and divider circuitry occupies the middle left area of the circuit board shown in Photo 1 with th
68. al using shadows to determine direction time as a compass S OURCES Using Time as a Compass www survivaltopics com survival using Eagle Schematic layout and autorouting software CadSoft Computer www cadsoftusa com ISL29102 Converter Intersil Americas Inc www intersil com ViewMate Gerber viewer PentaLogix www pentalogix com PCB Fab In A Box Kit Pulsar Professional FX www pulsarprofx com CIRCUIT CELLAR e www circuitcellar com Free SpYder Discovery Kit with an annual subscription to Elektor www elektor com cc PRESELECTOR FOR ELEKTOR SDR elio Here s the ME automatic tuning upgradel ENERCY SAVINGS FROM HoME AuroMATION m E EI Standards compared z n Technology mm m 2 E j j j II CIE UU S CHRISTMAS HoLIDAYS Cincuims n pages of beginner s and junkbox projects a BI D rou THE AWARD follow the stor T a Special Offer for Circuit Cellar readers Keep 68 50 in your pocket Subscribe to Elektor now f Sp der iura fur abere p 1 a a ET Creative fresh and unusual articles since 1961 T O Electronics projects to delight and educate in E les diverse areas of electronics O Each project is built tested and approved by Elektor s laboratory staff Access to a wide range of products to support magazine projects in our online shop O i You save 0 Magazines cll Mig i Double Issue July August e 6
69. alView Microcontroller Development Kit RVMDK and SafeRTOS from Wittenstein to create your design content entry and see how far your design will take you Stellaris EKK LM3S9B96 Evaluation Kit free with your contest entry while supplies last e No purchase necessary to enter e 10 000 in cash prizes e Entry deadline is June 23 2010 e Winners will be announced at the Embedded Systems Conference Boston 2010 e Submit your design today The EKK LM3S9B96 Evaluation Kit includes an evaluation board with an 80 MHz LM3S9B96 MCU featuring Ethernet MAC PHY CAN USB OTG and SafeRTOS in ROM a time limited copy of the Keil RealView Microcontroller Development Kit cables documentation and StellarisWare software m mom m HH m n ri m m ARM Cortex IKE AX gaeun For Complete Details Visit S NS m by Brian Millier RFID Based Liquid Control Part 1 Working with Off the Shelf Components With this article series you ll learn how to build an RFID based controller for monitoring dispensed liquid nitrogen from a tank Operated in a laboratory setting the system also bills customers for what they use This article details how to get started with some off the shelf components and simple code to transfer the transactions stored in the controller to a USB flash drive as standard files These files are readily imported into an Excel spreadsheet on a computer in our accounting office An alternate scheme would be t
70. an average of one wrong bit for each 100 bits then the probability of receiving a message cor rectly will be low even with hundreds of retrans missions The other difficulty is that this retrans mission method can t be used if the transmission is unidirectional Why The receiver would have no way to request that the transmitter resend the message The second solution is forward error correc tion FEC The idea is to add redundant data to the transmitted message so the receiver can Error counter Figure 1 The reference transmission system that used included an NRZ signal generator added Gaussian noise and a simple comparator receiver CIRCUIT CELLAR www circuitcellar com 0 40 7 0 35 7 0 30 7 0 25 7 0 20 7 0 15 7 Figure 2 A Gaussian curve is a natural model fo bility that the noise is above a certain threshold identify and correct transmission errors So the concept is that the receiver can work autonomously and obtain error free messages at least if the number of errors stays reasonably low without any retransmission Of course both methods retransmissions and FEC can be used jointly for even better performance AN Nia 1 5 1 0 r noise thanks to its statistical properties The proba x is noted erfc x You will not be surprised that FEC algorithms are used everywhere from a CD s encoding which uses the so called Reed Solomon FEC algorithm to server cl
71. ass RAM chips and also from GSM mobile phones to satellite communications In this article Ill describe the most basic FEC system Hamming codes I ll also present some Eb No 20dB mail iai 0 0 Eb No 0dB Figure 3 These histograms show you the effect of noise on the received voltage with a low top to high bottom level of noise Bit errors appear when both curves overlap www circuitcellarcom gt CIRCUIT CELLAR ideas about the most powerful codes to date BIT ERROR RATE amp AWGN Let s consider a very basic example see Figure 1 Suppose you have a mes sage encoded as a nonreturn to zero NRZ bit stream NRZ is a complicated way to say that the successive bits are simply transmitted serially with two voltage levels here they re supposed to be 1 V for zeros and 1 V for ones Add to this signal a random noise voltage with variable amplitude defined by its round mean square voltage You could then try to recover the data bits with a voltage comparator set at a 0 V threshold and sample the line voltage at a given point e g at the middle of the bit dura tion You should receive the same bit stream as long as the noise is low A note about the random noise gener ator The usual model used for such sim ulations of real life noise is the so called additive white Gaussian noise model AWGN The probability that the noise voltage is equal to a given voltage fol lows a Gaussian curve around z
72. at five letter conso nants only naming scheme PNDKR As I mentioned earlier PNDKR is really a simple board more of an FPGA breakout board than any thing else Other than RS 232 level translators the board just has a bunch of I O headers So I would say that any FPGA board with a suitable number of available I O pins can work One can even go onto an online auction and purchase an FPGA board pulled from some product A board schematic is not always required As long as you can configure the FPGA device pro vide it power reset and clock and Obtain access to an appropriate num ber of I O pins those are the main requirements One factor which militates in favor of finding a commercially produced board instead of making one is the growing number of FPGAs that are housed in fine pitch BGA packages These can be difficult to work with by hand Unless the BGA balls are brought out to headers or vias the FPGA cannot easily be probed on an oscilloscope or logic analyzer Nev ertheless one company Schmart Board provides a 400 pin board that purportedly allows hand soldering at a 1 0 mm pitch for those who wish to try their hand AUDIO OVER ETHERNET During the 2007 WIZnet iEthernet Design Contest I was tantalized by the possibility of interfacing an FPGA board with WIZnet s WIZ810MJ board for easy Ethernet connectivity I found that the embedded RISC PIC16F84 microcontroller interfaced with the WIZnet IC quite easi
73. ation Fourmilab www fourmilab ch documents calendar WWVB Transmitter and Data Format Specs NIST http tf nist gov stations wwvb htm NN Arduino Duemilanove Microcontroller board www arduino cc en Main ArduinoBoardDuemilanove CMMR G6P 60 WWVB Receiver Digi Key Part No 561 1014 ND C Max www c max time com Digi Key Corp distributor www digikey com www circuitcellarcom gt CIRCUIT CELLAR Learn CPLDS Bare the ir way with S plete kit comes with everything ou need to take you from mystery to mastery with CPLDs and programmable logic Learn to turn software into hardware OSD 232 RS 232 TTL controlled on screen composite video character and graphic overlay in a small 28 pin dip package AWSM tU i tive Circuits Intuitive Circuits www icircuits com 248 588 4400 Add USB to Your Designs Chips code protocols embedded hosts wireless options debugging USB 3 0 and SuperSpeed FOURTH JAN AXELSON Seir pen ceram oo USB Complete The Developer s Guide Fourth Edition Jan Axelson ISBN 978 1 931448 08 6 54 95 Lakeview Research LLC www Lvr com By the author of Serial Port Complete February 2010 Issue 235 5 qe EN RT A February 2010 Issue 235 by Bruce Land Floating Point for DSP For DSP and other fine grained parallel operations you need to pick a floating point representation and implement five basic operations
74. ations could be done in parallel eliminating the need for regis ters to hold the full set of round keys This won t work for decryption though because the round keys are needed in the reverse order That s why the key generation module stores the entire set of round keys A LITTLE HISTORY In 2002 the United States govern ment officially adopted AES The pre vious standard DES used a much smaller key 56 bits which became too small to resist cracking In addi tion because elements of the DES algorithm were classified there was suspicion that there might be a backdoor in the algorithm that would enable the government to crack private messages The AES algorithm is completely public with no known backdoors and no weaknesses beyond those inherent in a symmetric key cipher As a result AES has been widely adopted Whenever you communicate over the Internet using the secure socket layer SSL it s usually AES that s pro tecting your data Likewise when you communicate over an encrypted Wi Fi link you re using AES And it s the only security specified for 802 15 4 ZigBee wireless networks Communications isn t the only use for AES either It s commonly used to protect data in hard disks flash drives smart cards and even video and audio content In fact some hard disk scrub bing algorithms use AES generated data patterns to write pseudo random data to empty space on the disk to wipe out deleted infor
75. behind it in its wake Please contact JARO Thermal directly for pricing information JARO Thermal Www jarothermal com Embedded amp Networh Computing Technologies CAGAO BIN epo SYS A A AP CIRCUITS Low Power 100mA 5V As Tiny Form Factor 36 x 41 mm ME Two Boards Industrial Operating Temperature Range Two Layers 40 C 85 C m Two Masks e H each One Legend Unmasked boards ship next day www apcircuits com ELECTI l eicejizias mtu m Z leai lala POTS eS Ti 14 gt 9 VISA netaa Fe MEMBER ELECTRONICS INDUSTRIES Eg ao systems c www circuitcellar com CIRCUIT CELLAR February 2010 Issue 235 February 2010 Issue 235 HIGH PERFORMANCE 125 KHZ LF WAKEUP RECEIVER The AS53930 is a single channel low power low frequency wakeup receiver that offers the highest sensitivity at the lowest current consumption for the industry s best range The A55950 A83930 1 D LF Wakeup Receiver supports the widely used 125 kHz band and through the opti mization of power consumption sensitivity and programmabili ty enables a variety of applications The A55950 has a single receiving channel and an internal RC oscillator allowing a very low external component count for maxi mum performance versus cost and reduced size The received data can be correlated with a pattern that is programmed in the register preventing false wakeups Primary target applications are active RFID hi
76. code 890 output PORTA case 3 PORTA buffer 2 break end if end case end while Listing 2 This portion of the firmware defines the structure of the HID class of the Converter In essence the host computer will recognize the Converter device as an I O device and Listing 2 The main program prin cipally defines port D port B and port A of the processor to replace the three ports in a conven tional printer port It then transfers 3 bytes of data between the host and the processor buffers The direction of data flow depends on the code in the second byte The I O con trol information is in the third byte Figure 1 shows the main OxAl 0x00 OXUS 0x30 77 UX09 Uxol 7 UXLS OxXUD 75 Ux75 OXUS J Ux95 OxUS 7 UXxOl UXUZ 4 0X09 OX335 UxIS OXUS 77 0x95 UXUS 7 0X91 QOXUZ 47 0xC0 No February 2010 Issue 235 CIRCUIT CELLAR DIGITAL PLUS BONUS BONUS 0x26 OxFF 0x00 7 Logical The number of bytes in this structure is hard coded in device h rom struct byte reportLHID_RPTO1_SIZE hid_rpto0l 0x05 0x01 Usage Page T 0x09 0x05 Usage Collection fi Usage X Usage Y Logical ui Minimum Maximum Report Size Report Count Input Usage Rx Report Size 8 Report Count 5 Output End Collection CIRCUIT CELLAR www circuitcellar com ANO RAO VREF CVREF ANZ RA2 VREF AN3 RA3 TOCKI C1OUT RCV RA4 SS HLVDIN
77. computer recognizes the unit as an additional serial port as indicated in the Win dows hardware manager The firmware in the microprocessor handles everything End users don t have to know a thing about USB communi cations All you have to do is to make sure that the applica tion program is addressing the correct COMM port number GET CONTROL In this article I outlined a simple method for harness ing the power of USB technology for computer control applications Once loaded with the provided firmware a Microchip Technology PIC18F4550 with a handful of electronic components can be readily converted into a plug and play control device in Parallel or Serial mode My objective was to take away the technical if not mys terious firmware driver details associated with USB peripheral development You can now continue working with ease on computer port control applications sl i February 2010 Issue 235 CIRCUIT CELLAR DIGITAL PLUS BONUS BONUS Listing 3a Both the Converter Control Program and a typical Parallel Port Control Program b are listed for easy comparison a Rem USB Parallel Converter Chan Private Sub Commandl_Click Dim data pd cd As Byte Dim pn As Integer HIDComm1 Connect ParallelControl Show pd CByte Textl Text cd CByte Text2 Text pn pd If pn lt 1 Or pn gt 3 Then pn 1 Call CallPort pn cd HIDComml Uninit End Sub Private Sub CallPort pn As Integer Dim Buffer As B
78. conds Linux 2 6 and Debian by default Low Price Low Power High Reliability using Linux development tools 200 MHz ARM Family Power as low as 1 4 Watt NEM 757200 8 boards over EE shown with 3 d optional A D 2000 configurations converter Compact Flash NN suo Fanless no heat sink SDRAM up to 128MB Flash up to 128MB onboard 10 100 Ethernet up to 2 a SD card option DIO lines up to 55 a 2 USB ports a VGA video a COM ports up to 10 a options include LCD read onboard temperature sensor A D Converter 8 channel 12 bit Extended Temperature Battery Backed Real Time Clock USB Flash USB WiFi a Programmable FPGAs a Linux Real Time extension Debian 7 Over 20 years in business 3 Custom configurations and designs w 3 Open Source Vision excellent pricing and turn around time 3 Never discontinued a product l P 3 Most products stocked and available 3 Engineers on Tech Support for next day shipping Design your solution with one of our engineers 480 837 5200 TS 7500 Our Smallest Computer 250 MHz ARM9 at Our Best Price Point Low power fanless 2 watts 64MB DDR RAM 4MB NOR Flash Micro SD Card slot SDHC USB 2 0 480Mbit s host 2 slave 1 10 100 Ethernet Boots Linux 2 6 in 3 seconds Customizable FPGA 5K LUT Power over Ethernet ready Optional battery backed RTC 74 3 mm 2 925 in Watchdog Timer 8 TTL UART 66 mm 2 600 in 33 DIO SPI I2C Lect 400 MHz PowerPC
79. copper covered laminate which when exposed to acid prevents the acid from etching any copper that has been masked The mask begins as a Gerber file imported to the PentaLogix View Mate a free Gerber file viewer that enables multiple layers to be imported and displayed When producing a double layer PCB two layers are imported the top and bottom These are displayed one on top of the other You must select one layer and move it to the side so there is about a 2 space between them If the PCB is any larger than about 4 x 7 you have to print each layer as a separate sheet because both layers won t fit on a single 8 5 x 11 sheet The advantage to printing both layers together on the same sheet has to do with registration Because the mask will actually be retransferred to the PCB laminate after it is printed on paper you must first mirror image the masks before printing Print the display to a laser printer with a 1 1 ratio The key here is the toner in the laser printer An Inkjet won t do The printing process will place the mir rored top and bottom layer on a sheet of paper This page will be used as a holder for a piece of transfer medium toner transfer system TTS As you can see in Photo 2 I used less than a full 8 5 x 11 sheet of TTS The TTS is like a sheet of decal material You ve decorated plastic models right The laser printer transfers its toner melted plastic to the TTS just as if it were paper The differ
80. ctical guide for Hobbyists Engineers and Scientists wishing to build measurement and control systems to be used in conjunction with a local or even remote Per sonal Computer The book covers both hardware and software aspects of designing typical embedded systems based on personal computers running the Windows operating system It s use of modern techniques in detailed numerous examples has been designed to show clearly how straightforward it can be to create the interfaces between digital and analog electronics programming and Web design Hardware developers will discover how use of latest high level language constructs overcomes the need for specialist programming skills Software developers will appreciate how a better understanding of circuits will en able them to optimize related programs including drivers There is no need to buy spe cial equipment or expensive software tools in order to create embedded projects covered in this book 292 pages ISBN 978 0 905705 79 8 46 00 Prices and item descriptions subjectto change E amp O E C 2008 AND NET PROGRAMMING FORELLrCTRONNM ENGINEERS e lektor Learn more about C programming and NET C 2008 and NET programming This book is aimed at Engineers and Scientists who want to learn about the NET environ ment and C programming or who have an interest in interfacing hardware to a PC The book covers the Visual Studio 2008 develop ment environment the NET framew
81. d 011 The three error correction bits are called the Hamming syndrome Then just transmit the 7 bit message The beauty of this mechanism is on the reception side see Figure 6 In this instance the message is 1011 and the calculated syndrome is 001 so the trans mitted message is 1010101 Let s sup pose that the third bit was received in error and you get 1000101 Then calcu late the syndrome of the actual received packet with the same algorithm as in the transmitter You will find 100 as shown Calculate a bit per bit exclusive OR of this calculated syndrome 100 J Lj h Figure 5 A Hamming encoder uses bits at positions 001 010 and 100 as FEC bits Each FEC bit is calculated as a parity of all data bits at a position that has the same bit set CIRCUIT CELLAR e www circuitcellar com with the received syndrome 001 This gives 100 XOR 001 101 And 101 is the binary position of the bit that was in error Just invert this bit and you get back the error free message Bingo As these operations are all basic binary XOR and addressing I am sure that you ll be able to design a Hamming FEC encoder or decoder in hard ware even using TTL gates or code it in your preferred Invert the faulty bit 111 110 101 100 O11 No more errors microcontroller I encourage you to check this algorithm with other errors even with an error in an FEC bit You ll find that such an FEC can correct any si
82. d communication challenges analysis of software quality www keil com Easy to use from concept to final product e MDK ARM is an Integrated Development Environment for ARM and Cortex M microcontrollers RL ARM is a Library Collection designed to solve real time ULINKpro is a high speed Debug and Trace unit for detailed 800 348 805 PIRE February 2010 Issue 235 oO Q February 2010 Issue 235 EB No dB Figure 7a The use of a Hamming 7 4 code requires more bits to increase the bit rate which degrades the BER when the FEC decoder is not switched on b With FEC in action the BER is significantly reduced But there is an improvement over the non coded version only when the signal to noise ratio is high enough The gain is around 0 5 dB for low error rates code For example if you replace the 7 4 Hamming code by a 15 11 code meaning 11 bits of data and 4 bits of error code the theoretical asymp totic gain jumps to 1 46 i e 11 15 x 1 1 or 1 6 dB Figure 8 shows the corresponding simulation CONVOLUTIONAL CODERS Hamming codes are only the begin ning More optimized forward error cor rection systems use sophisticated linear block coders convolutional coders or both Convolutional coders are quite complex but I ll highlight a few impor tant points Refer to Figure 9 On the transmitter side the idea is to calculate a derived bitstream from the input using
83. dB down Figure 3b shows the output after the filter again routed through the modu lator the third harmonic is now down to 44 dB The filter does a better job than presented here because the mod ulator introduces some harmonic dis tortion but the output is certainly clean enough for my purposes NKR A 121 8 kH 43 5 dB d STOP 60 8 kH SUP 197 mee Figure 5a The 60 kHz square wave output of IC1A shows the expected harmonic content b The filter reduces the third harmonic by more than 55 dB considerably cleaning up the output The modulator contributes some additional harmonic distortion www circuitcellar com CIRCUIT CELLAR A February 2010 Issue 235 With a good looking carrier in hand it s time to combine it with some PWM data DATA MODULATION The NIST WWVB transmitter locks the data bits to the carrier wave form but by the time the signal passes through their antenna and travels halfway across the conti nent that relationship is largely irrelevant The C Max WWVB receiver specifies a 35 ms pulse width toler ance roughly 2100 carrier cycles so precise PWM timing wasn t really an issue even for my local signal Because the PWM pulses are all mul tiples of 100 ms I routed the 60 kHz carrier to the Atmel ATmegal68 s T1 input I used the inverted output of IC1A rather than the non inverted signal undergoing analog filtering Timerl then divides the frequency by 6000 to pro
84. de analog input and output ranges 40 C to 85 C Standard Cow mmm Order 24 7 fast and easy ot through Goog A wow stt 04 com Apex Embedded Systems help stx104 com 608 256 0767 x24 Welcome to the Designer s Notifica tion Network Print subscribers are invited to join the Network tor advance notice about our new sample distribution programs Find out more at www circuitcellar com network February 2010 Issue 235 m CIRCUIT CELLAR www circuitcellar com aural Wd EL eee Inside great products Behind great ideas phyCORE System on Modules shorten time to market reduce development costs and avoid substantial design issues and risks Windows Embedded CE and Linux BSPs processor dependent 129 unit benchmark price at 1K for ARM9 based SOM Design Services available to assist with deployment into target applications ARM11 i MX35 i MX31 ARM9 i MX27 LPC3250 LPC3180 Cortex M3 STM32F103 ARM7 LPC2294 XScale PXA270 x86 Z510 Z520 Z530 Atom Blackfin ADSP BF537 Coldfire MCF5485 PowerPC MPC5554 MPC5567 phyCORE LPC3250 MPC5200B MPC565 MPC555 phyCORE Rapid Development Kits include SOM Carrier Board LCD kit specific schematics software free BSP for applicable kits and a start up guarantee The Carrier Board serves as a target reference design allowing the SOM to easily port to the user s target hardware www phytec com 800 278 9913 www phyc
85. different key for each round makes the encryption significantly stronger because it s almost the same as using a much longer cipher key Using an expanded key generated from the smaller cipher key has two other advantages One a smaller cipher key is easier to communicate and keep track of Two the key expansion process can compensate for what would otherwise be weak keys Think of the case where someone inadvertent ly picked a key of all zeros Before I dig into the details of the algorithm let me point out the most important fact to remember when dealing with encryption the original data cannot be destroyed So no matter what the algorithm does to those original 128 bits of data by shuffling the order of the bits or combining them amongst themselves in convoluted ways or combining them with bits of a key the original data bits are all still there Figure 1 The 128 bit data block is contained in four 52 bit regis ters In this implementation all 128 bits are operated on in parallel simplifying the storage requirements and increasing performance CIRCUIT CELLAR www circuitcellar com In a practical sense what this means is that the only kind of operations available for encryption are inversion and Exclusive OR XOR This fact makes the basic operations used in the AES algorithm much easier to imple ment but more difficult to understand because you have to remember that terms like add and multiply
86. drew Viterbi in 1967 the idea is to search intelligently through all possible paths of the input bits to find the one most likely to provide the received datastream even in the presence of ran dom errors For more information about the Viterbi algorithm refer to the arti cles cited in Resources section of this article Charan Langton s tutorial titled Coding and Decoding with Convolutional Codes is particularly useful I didn t code a convolu tional coder in SciLab but I grabbed one from the SciLab website thanks to its author Antoine Blais for the contribution and integrated it into my simu lation code Well as I expected the computations were far too extensive so I had to reduce the number of simulated bits from 200 000 to 20 000 I went to sleep after clicking on the Run button It was a good 1 6 dB idea because the resulting plot appeared around 4 hours later see Figure 10 The result was impres sive There was no single bit in error for SNR ratios above 6 dB during the simulation time The asymptotic gain was probably around 3 to 5 dB but it couldn t be deducted without a far longer simulation or a mathematical analysis The Viterbi algorithm can also implement an important improvement Here the decoding was made using the received bitstream data bits and FEC bits But in a real radio receiver there is additional information the strength of each bit For example some bits can be received
87. ds computer mice and audio video instru ments are just some of the examples supported by the HID class Microchip also offers HIDComm ActiveX as a simple communicating channel in a control program between its microcontrollers and host Incredibly Microchip even provides a free MPLAB package to sea soned designers for programming simulating and diag nosis purposes FIRMWARE The majority of USB handling routines in the project firmware comes from Microchip libraries The only two parts to be considered in the printer port converter firmware are the control ling main and the HID dec larations The essential por tions are listed as Listing 1 Listing 1 This is the essential routine in the firmware main pro gram which tells the processor of the Converter how to decode the three incoming control bytes void main void Int Te I int len byte theDelay byte bdata char buffer 3 char mybuffer buffer PORTD 0 TRISD Us bdata 0 len 3 declare PORTB as inputs TRISB 255 ctriCount word 0 InitializeSystem while 1 USBTasks USB Tasks receive 3 bytes from host routine bdata HIDRxReport mybuffer len emulate only if data were received if bdata gt 0 emulate print port routine switch buffer 1 port code 888 output PORTD case 1 PORTD buffer 2 break port code 889 input status in PORTB case 2 buffer 2 PORTB if ImHIDTxIsBusy HIDTxReport buffer len j break port
88. duce an interrupt every 100 ms whereupon an interrupt han dler generates the PWM output by tog gling an output bit The Arduino run time routines occasionally disable interrupts around critical sections of the code which introduces several microseconds of jit ter on the leading and trailing edges of each PWM pulse Compared with the vagaries of RF propagation and the receiver s internal jitter those delays simply don t matter The carrier power drops by 10 dB a voltage ratio of 3 2 during the PWM pulse so the modulator must produce only two output levels full power and 10 dB I used a venerable LM386 as a modulator and power driver although it normally serves as a low power audio amplifier capable of driving a few hundred milliwatts into a 4 O load The schematic in Figure 4 shows that I powered it from the raw 9 V supply to isolate it from the usual hash on the digital logic supply and provide more headroom for the output signal The ATmegal68 output bit drives K1 a MOSFET relay to vary the amplifier gain When the bit is high the relay is off and the LM386 has its 60kKHz Carrier iN February 2010 Issue 235 Low high gain TPS C18 C19 TP11 R17 Antenna Drive X1 1 l 3 9 10u C15A C15B C15C C15D Choose capacitor to resonate antenna Figure 4 The LM586 low power audio amplifier has ample bandwidth for a 60 kHz signal The optical relay switches in an RC network to boost the qa
89. e a design that s the same as the first but throw out JTAG debugging After all you can load code in different ways Three choose a design similar to the first two but also throw out cycle accuracy You really just want it to function correctly After all what are a few cycles between friends Four choose a design that s instruc tion set compatible but not code library compatible In other words eliminate the package constrained ports and begin to set up I O for the microcontroller the way you really want it After all it s inside an FPGA now so you needn t be limited to ports A B and C Add a few new ports into the memory map Obviously this choice may require custom SW coding or modifying existing code libraries somewhat Five you have control of the CPU instruction superset Consider adding new instructions And six add tightly coupled hard ware accelerators to take workload off of the processor After all you can completely halt and restart the proces sor on a cycle by cycle basis if desired This list should inspire some cre ative ideas and help you think out side the box As you ll see I chose to work at level four from the aforemen tioned list Also you can pipeline the design or not to whatever level you choose DEBUGGING ENVIRONMENT Initially I was stumped when my UART wasn t responding properly So I borrowed a logic analyzer and saw what was happening As luck would have it
90. e crystal flat on the board I soldered its case to the ground plane to provide both mechanical stability and some RF shielding although the latter is likely superfluous in this application Because a square wave has very high harmonic content however it s a F440 v3 OCT 20873 7 REF 2 0 dEn not the sort of signal you want to feed directly into a transmitter Even for my very low power transmitter I wanted a sine wave Carrier with reasonably low harmonics It s time for some filtering CARRIER PURIFICATION RF filters generally resemble small sculptures helical copper wound inductors surrounded by lumpy capac itors Because the 60 kHz WWVB car rier frequency would require relatively large inductors and capacitors I used a MAX274 active filter chip You could achieve much the same result with a design using separate op amps The MAX274 is what s called a mature chip to the extent that its design support software was written for 386 class PCs and VGA displays I wasn t too surprised to find that the Linux dosemu virtual machine han dles it perfectly producing a very nice graphical display Figure 2 shows an 8 order Butter worth 60 kHz low pass filter I set the cutoff gain to O dB rather than the usual 3 dB simply because the input signal was a square wave with essen tially no DC content The filter circuitry occupies the lower right corner of the board in Photo 1 The datasheet cautio
91. e each issue of Circuit Cellar except for the death part Let s say that while reading a project centric article you become so interested in a part that you immediately go to the manufacturer s website That s one adventure Now imagine that instead of checking out the part you decide to get more information by emailing the author That s another adventure The great thing about Circuit Cellar is that each issue provides the possibility for dozens of engineering adventures You re in charge I urge you to approach this issue in the spirit of choosing your own adventure Are you ready Let s begin Turn to page 16 to learn how to build an RFID based moni toring and control system Brian Millier describes how he designed a wireless control system for a liquid nitrogen tank To learn how to start an FPGA based embedded design jump to John Clayton s article on page 24 He covers topics ranging from custom development environments to HDL coding syn thesis tools For more FPGA related content check out Bruce Land s article on page 46 Skip to page 30 to learn why Tom Cantrell says many MCU suppliers are betting on the ARM Cortex M3 Are you with them On page 38 Ed Nisley presents a totally fea tureless clock design which requires you to first build a WWVB simulator Are you fascinated in the Advanced Encryption Standard AES but put off in the complicated math You aren t alone Go to page 54 for Monte Dalrymple s useful presentation o
92. e easily run from the PC that help alleviate the drudgery After all if it s no fun why pursue it as a hobby or otherwise SIMULATION OR NOT With the rs232 syscon core and some ready made parameterized and configurable register blocks up the designer s sleeve a Module Under Test can be run through its paces using the actual target FPGA instead of a simulator Figure 1 shows the concept I used I will not deny that simulations work like a charm But I will say that it takes time to put together a really good simulation test bench It takes more time to carefully run and analyze the simulation both pre and post synthesis And in the end there may well be some sort of real world gotchas that just weren t covered by the simulation For exam ple will a frequency doubling PLL All parameters are in hexadecimal correctly lock Very few simulations will give good satisfaction on this type of question Personally I want to know about those real world gotchas as early as possible so I m suggesting you get the code compiled and the bit stream loaded into the FPGA and start debugging ASAP DEVELOPMENT MODULES As I previously stated there are two major components which work togeth er in this firmware based development environment the rs232 syscon which is the system controller and the register blocks which form the bound ary between the development environ ment and the new logic or IP core under t
93. e hot sellers low power CIRCUIT CELLAR www circuitcellar com vector to three phase conversion PWM automatic task sequencing for field oriented motor control algo rithms see Figure 2 As a result the 370 is said to consume less than half the M3 cycles of a software only implementation freeing application software to focus on higher level control and extra features e g con trolling a second motor By contrast the TMPM360 is notable for what it doesn t include Targeting the bluest of blue collar apps there s no Ethernet USB CAN radio etc But what the 360 lacks in fancy I O it makes up for by dou bling down with the basics Versions are available with up to 2 MB flash and 128 KB SRAM a natural for spiff ing up yesterday s boring LCDs with some memory intensive eye candy When it comes to standard I O the 860 goes all in calling a designers bluff with a big stack of peripherals including up to 12 UARTS five PC ports 16 timers and 16 input 10 bit ADC LEAN MEAN amp GREEN The M3 bandwagon is big enough for young and old alike Say hello to newborn Energy Micro see Photo 6 As the company name implies they aspire to be the Energizer Bunny of M3 flash MCUs by taking a hard look at every electron that dares to make a move Now it s not as though other chip companies don t get the picture that green is the new black Every mod ern MCU takes advantage of lower volt
94. e provides an equivalent gain in terms of SNR of 0 5 to several decibels depending on the code s complexity These are not small gains For example a 3 dB gain in a radio frequency link s budget will increase the open field maximum distance by 4096 not too bad without any significant hardware changes Concatenated FEC codes are usually used to achieve even more impressive results The idea is to use a convo lutional code for the main error correction and then add an outer error correction code usually a strong linear block code to correct the remaining errors For example the aforementioned Voyager space mission used a 1 2 rate convolutional code followed by a Reed Solomon 1023 bit code in order to get a BER of 10 with signal to noise ratios as low as 2 5 dB Newer codes like turbo codes can achieve the same impressive BER with an even higher level of noise up to a signal to noise ratio of O dB or lower which means more noise than signal Some code can be difficult to implement and computer intensive Other code can be quite simple and can drasti cally improve your system s performance or reliability I hope that these techniques are no longer on the darker side for you Experiment FEC in your next project al BER over Eb No convolutive length 5 rate 2 6 EB No dB Figure 10 Here is the simulation of a basic convolutional code with a short k 5 length and a ratio of 1 2 Impressive isn t it WWW circuitcella
95. e s also a Low Energy UART that runs off the 32 kHz RTC clock The low frequency limits the bitrate but the UART can keep up with a 9 600 bps connection while consuming a mere 100 nA YOUR DEAL I gave a conference presentation a few years back titled Is ARM the 51 of Tomorrow My conclusion was yes and no Yes in the sense that the openness of the architecture and a bandwagon of suppliers is a boon for business No in the sense that unlike the 51 the M3 benefits from having an owner i e ARM Inc to keep the bandwagon rolling In my conclusion I predicted that ARM wouldn t eliminate the competi tion witnessing the fact the 51 didn t either But I also said ARM can cap ture the largest share of a market that s going to grow quickly and last a really long time I ll stand by that today One thing is for sure whatever application game your playing six M3 flash MCU suppliers of a kind sure seems like a winning hand al Tom Cantrell has been working on chip board and systems design and marketing for several years You may reach him by e mail at tom cantrell amp circuitcellar com P Ens T Cantrell Is ARM the 51 of Tomorrow Presentation ARM Develop ers Conference October 4 2006 S OURCES mbed Microcontroller rapid prototyping tools ARM www arm com SAMS3U Cortex M3 flash MCU Atmel Corp www atmel com Sensor Network Analyzer SNA Daintree Networks w
96. e the MAC operations for SOS one State 5 updates the history registers for SOS one and couples SOS 1 to SOS 2 States 8 to 12 compute the MAC opera SOURCES tions for SOS two State 13 updates the Altera University Program Quartus II download and information on hard history registers for SOS 2 and couples ware Altera Corp www altera com education univ unv index html SOS 2 to the output register Listing 3 is a two pole version of the code ECE57060 Floating point page http instruct1 cit cornell edu courses ece 576 FloatingPoint index html 5 E J Ehliar et al Using Low Precision Floating Point Numbers to Reduce Memory Cost for MP3 Decoding IEEE 6th Workshop on Multime dia Signal Processing Linkoping University Sweden 2004 www da isy liu se pubs eilert eilert mmsp2004 pdf 18 BIT FLOATING POINT ise Tos dodge E bed ECE5760 Main page Cornell University http instructl cit cornell edu here allows up to 70 floating point conie UD E multipliers and around 150 floating A Penmetcha and S Pryor Graphics Processing Unit ECE5760 Cornell point adders to be placed on the University http instructl cit cornell edu courses ece576 FinalProjects 33 000 logic element Cyclone II FPGA 2008 ap328 sjp45 website introduction htm which is standard on the the Altera DE2 educational development board VHDL 2008 Support Library EDA Industry Working Groups www eda org fphdl At a 30 MHz clock rate this would
97. eeded TCP IP offload ICs improve system performance DS1000E 25MHz 2 ch 16 logic scope and logic analyzer 1195 PS2104 PS2105 Windows PC LX800 512MB 4GB Ethernet 3xUSB SD Mephisto 100MHz Scope Spectrum Logic Analyzer and Signal Generator 1259 12C Xpress Kits turn your PC into vehicle electrics diagnostic tool USB Loggers H ao Standalone USB temp hum volt current loop datalogger 49 CAN USB MSR145S FT232RL Intelligent CAN connection from PC s USB port 299 IZ110SR W5100 UDP IP controlled 24 digital I O board 3 x 8 bit TTL ports uOLED 96 G1 DS1052D EL USB 1 2 3 4 PS3423 KLARI MOD CAN USB AWME6EXX TX RX Amazing 7 in 1 Scope CircuitGear CGR 101 is a unique new low cost PC based instrument which provides the features of seven devices in one USB powered compact box 2 ch 10 bit 20MS sec 2MHz oscilloscope 2 ch spectrum analyzer 3MHz 8 bit arbitrary waveform standard function generator with 8 digital I O lines It also functions as a Network Analyzer a Noise Generator and a PWM Output source What s more its open source software runs with Windows Linux and Mac OS s Only 180 microCAM Multichannel DAQ a 12 16 input 1kS s 10 12 bit PC connected voltage logger EMC Spectrum Analyzer Handheld Palm PC based 2 7GHz Spectrum Analyzer Compact compressed serial output camera module for any host system EMC Spectrum Analyze
98. efore requires a total control range of the difference between the minimum and maximum 500 us If the maximum movement is 360 and you want to control the move ment in tenths of a degree you will need to control the PWM s resolution to 3 600 i e 360 x 10 parts within this small part of the total PWM time Suppose you can use a 2 048 ms PWM period Using the maximum 10 bit reso lution on the PWM that would give you a 2 us resolution over the 2 048 ms range If a servo requires a signal between 1 250 and 1 750 ms a 500 us range which means each bit of con trol will move the servo 500 us 2 us or 1 250 of its total range If that range is 360 then each bit moves the servo 360 250 1 44 which is the angle through which the sun moves in 6 min utes Hmm That s something to think about for next month Jeff Bachiochi pronounced BAH Key AH key has been writing for Circuit Cellar since 1988 His background includes product design and manufacturing You can reach him at jeff bachiochiGimaginethatnow com or at www imaginethatnow com R ESOURCES Microchip Technology PIC16F193X LF193X Data Sheet 28 40 44 Pin Flash Based 8 Bit CMOS Microcontrollers with LCD Driver and nanoWatt XLP Technology DS41364C 2009 Sundial info Thunderstruck Observatory http com sundials index html thunderstruckobservatory Survival Topics Using Shadows to Determine Direction www survival topics com surviv
99. ence is that the TTS releases the mask when soaked in water see Photo 3 However before putting the TTS in water you must transfer the mask remelt it onto the PCB laminate I put both layers of the mask on the same sheet of TTS so I can fold it in half with the toner on the inside This eliminates having to match the two images in the rotational direction I still slightly adjust the crease to bring the two images in registration with one another in the X and Y directions To do this I hold the TTS up to a bright light source e g a flashlight or sunlight preferably some thing that does not give off heat otherwise the two images would remelt and stick together You must move the images using the free ends of the folded TTS until the two images are registered that is the via s pads on one layer line up exactly CIRCUIT CELLAR www circuitcellar com with the via s pads on the other layer Once you have perfect alignment adjust the crease and tape the free ends of the TTS with a piece of transparent tape to prevent the layers from shifting You now have a little pouch of TTS with a crease on one end and the opposite ends taped together Cut a small piece of PCB laminate at least 0 5 bigger than the artwork Smoothed any roughness along the edges with a fine file clean the sur face of any oils and polish the copper surface with a nonmetallic scrubby green pad Now insert the laminate into the folder TTS Make sure i
100. endent controls back on the dash that were once all incorporated in the single iDrive control In my opinion BMW simply got carried with the we can do it mentality and forgot the customers guess the lesson is that unless your business is pure technology implementing new technology simply for the sake of imple menting it is a risky strategy While it s true that new gadgets and software have made our lives much more efficient and have given us the ability to do things we never thought possible replacing the tried and true dual slide toaster controls temperature and dura tion with a keypad LCD and 10 page user manual is ludicrous I believe there are a few like this actually on the market In my opinion subverting simplicity with bloated and overly complicated technology is ridiculous Technology and process are interdepen dent and need to be kept in balance The most productive and economically successful product designs are those that suit the busi ness purpose without radically bending the design process or adding an unnecessary inflated feature set simply to experiment with new technology The best designers are the ones who don t forget to add a little bit of old fashion human judgment and common sense to the final product After all that introduction you might expect that this is the point where detail the 10 point plan for solving the feature creep men ace but frankly I d be a hypocrite if attempted to do that can certainly poin
101. ero see Figure 2 Throw a die 100 times sum the results repeat the test 100 times plot the histogram of the sums and you will get a Gaussian curve So this is a reasonable model of noise With a Gaussian model the noise voltage can be extremely high but the probability that it exceeds a given threshold becomes lower and lower when the threshold increases It follows the erfc function see Figure 2 For example with a l V ums noise the probability that the noise exceeds 1 V or 1 V is calculat ed as erfc 1 15 7 The probability that it will exceed 3 V is erfc 3 0 00296 That s low but not null What happens when you increase the noise voltage As long as it stays low the noise spreads the bit voltage around its nominal value but the prob ability to cross the comparator thresh old is low so few bits are erroneous see Figure 3 However when the noise voltage increases this probability increases following the erfc function More exactly it s half because the threshold is only crossed on one side of the Gaussian curve For example if the noise voltage is 1 V the bit error rate is expected to be 7 8 i e 15 796 2 February 2010 Issue 235 e WwW BER over Eb No no fonward error correction t EB No dB Figure 4 This is the theoretical bit error rate for an NRZ trans mission as a function of the signal to noise ratio plain line as compared to the result of my simulation
102. ers had f coeff lt b13 the correct frequency response and rn i lt A nex state were free of artifacts I could be rea P eS ta sonably sure that the modules were end working correctly At first I tried to sr tch the f f th ao matc e frequency response of the PRE ip SIP three filter types using a naive f_mac_old lt f_mac_new UT 1 f_coeff lt al2 Direct Form II Transposed form qo WM similar to the Matlab filter function next state It worked for the second order filters ond state lt 4 d but failed for the higher order filters 5 because the 9 bit mantissa did not begin e set up al3 y n 2 carry enough precision to represent ee coro qe EU S the filter coefficients f coeff lt al3 The solution was to factor the fil f value lt fl y n l next state ters into second order sections SOSs state lt 4 d6 SOSs typically have coefficients end which require lower accuracy but R more dynamic range perfect for this get the output of the first SOS floating point Once rewritten as and put it in the LAST output var OSs thelerau trequencies and for the next pass thru the state machine q fl y nl lt f mac new phase shifts were close to the calcu apply the final gain mult f value lt f mac new lated values implying that the float quu eee ee ing point was working Figure 2 shows update output history a 4 order Butterworth response com flyn lt fl_y_nl update input
103. es together You are probably familiar with the various USB serial and USB parallel chips modules which the company also makes You ll find them embedded in many commercial products including many microcontroller evaluation boards and device programmers for example The USB serial and parallel chips mod ules are USB slaves that is they re meant to be plugged into a USB host controller which is in most cases a computer of some sort The main pur pose of the USB serial device is to enable a manufacturer to modernize a design that includes an RS 232 data link into one that communicates via USB Many newer computers no longer contain seri al ports but have numerous USB ports The Vinculum line is different in that it implements a USB host controller as well as other functions Thus if you are using a microcontroller you can easily connect a great variety of low cost con sumer devices e g such as flash drives and HID class devices without having to worry about adding the USB host con troller protocol to your firmware The Vinculum line starts out with the VNCIL USB host controller chip This contains two USB 2 0 ports which can be configured in either Host or Slave mode This enables you to connect a USB flash drive to your microcontroller based CIRCUIT CELLAR www circuitcellar com design It also allows you to connect your device to a PC to upload or down load data or program information The VNCIL chip is
104. est Describing the rs232 syscon module is easy because its purpose is to pro vide the world s simplest command line There are three commands read write and initialize The syntax is parameterized so it scales according to the way the module is instantiated see Table 1 The UART function is designed with simplicity in mind a simple TX RX and GND interface without double buffering or flow control of any kind I trust I haven t offended anyone by also conveniently leaving out the parity bit and fixing the UART trans fer size at 8 bits After all its just for simple debugging I am particularly proud of the auto matic data rate generator inside this module because it synchronizes to whatever data rate it sees from the host terminal even nonstandard speeds It does this by checking the received intervals of each character filtering out and rejecting the charac ters that do not match what it is look ing for which happens to be an enter character technically the car riage return OxOD If the relative sizes of the intervals within the received candi date character match those Command Parameter 1 Parameter 2 Parameter 3 Comments of an enter character which aaaa qq Read starting from address aaaa quantity qq items are known a priori the mod aaaa dd qq Write starting at address aaaa data dd quantity qq times ule decides that the candi Table 1 The
105. etting up a simple custom microcontroller development environment Along the way I ll also present some ideas for an easygoing approach to design and development THE INGREDIENTS All you need to get started with embedded design using FPGAs is a PC some HDL coding synthesis tools and a suitable FPGA board to download to Several suppliers have parts that are suitable for developing a small custom microcontroller environment Obviously the larger FPGAs will allow instantiating more logic Multicore anyone and hardwired multipliers will often aid in the pursuit of high er execution speeds The board design I used is also given out free and there s a user s manual describing the board One word of warning though There s no schematic It s basically an FPGA breakout board with the download N A cable built right in In this article I ll first describe the rationale behind my slightly unusual approach to FPGA design Then I ll explain how I built up a system of building blocks that eventually became the trusted foundation on which I built and refined an embedded Microchip Technology PIC16F84 compatible embedded microcontroller The complete code for the design is provided in Verilog and you can use many of the same blocks to build your own designs The code is posted on the Circuit Cellar FTP site If VHDL is the pre ferred language I ll leave the translation as an exercise for you I use both languages and
106. exed LCD Accomplishing this requires light sensors positioning mechan ics DIY PCB production driving LCD segments and just a bit of astrophysics 100 000 lux SUN SENSOR Let s begin with how to create a directional light sensor Quadrant sensors can combine four sensors on a single die These are typically used for position sensing a laser beam and they can be expensive These sensors require a beam size smaller than the diameter of the sensing array Using the principal of the pinhole camera you can get the sun s beam down to a few millimeters in diameter but I like using shad ows to allow for much wider off axis detection while still providing fine on axis differential positioning I chose a device that has a spectral response close to the human eye and a wide input range The Intersil ISL29102 is a low cost light to voltage silicon optical sensor that combines a photodiode array a nonlinear current amplifier and a micro power op amp on a single monolithic IC The sensor package is about the size of a grain of rice and therefore requires patience to mount but it provides the basis for an inexpensive tracking module It has a flexible voltage supply requirement of from 1 8 to 3 3 V which yields a nonlinear output over an input luminance range from 0 3 to 10 000 lux Table 1 includes a few examples of typical luminance levels The ISL29102 has one control input The REXT input selects a scaling constant that lets you adjust
107. f the AES If you re confused by the topic of forward error correction FEC refer to Robert Lacoste s article on the subject p 62 It s a great introduction to the subject Jeff Bachiochi wraps up the articles section of the issue with the first installment of his Sun Tracker article series p 68 This project enables you to tell time with a mixture of old and new technologies Sundials sensors and MCUs Now that s a bill of materials bound to lead to an amazing design adventure As usual we have a lot of handy information packed in a single issue You can t build all the projects and test all the the ories at once so choose your adventure wisely There s no rush You can always return to the issue to start a new journey Mbit cj circuitcellar com A February 2010 Issue 935 THE MAGAZINE FOR COMPUTER ARE ie ADVERTISING 800 454 3741 978 281 7708 www circuitcellar com advertise ADVERTISING REPRESENTATIVE Peter Wostrel Strategic Media Marketing Inc 1187 Washington St Gloucester MA 01930 USA 800 454 3741 978 281 7708 peter smmarketing us www smmarketing us Fax 978 281 7706 ADVERTISING COORDINATOR Valerie Luster E mail val luster Q circuitcellar com Cover photography by Chris Rakoczy Rakoczy Photography www rakoczyphoto com PRINTED IN THE UNITED STATES CONTACTS Information www circuitcellar com subscribe E mail subscribe G circuitcellar com Subscribe 800 269 6301 ww
108. gh value asset tracking real time location sys tems operator identification and access control or keyless entry The A55950 wakeup receiver is available in a TSSOP16 or a QFN 4 x 4 package It is suitable for operating environments ranging from 40 to 85 C The A55950 is priced at 2 50 each in 1 000 unit quantities austriamicrosystems AG WWW a ustriamicrosystems com ETHERNET DATA RADIO The SureCross DXERY Ethernet data radio is an industrial qrade long range QOO MHz radio used to create point to multipoint configurations of wireless Ethernet networks The DXERO9 is designed for industrial applications and will perform reliably in applications that prove too noisy or too far for standard Wi Fi based systems This is a high gain system that has over 10 times the range of a Wi Fi network It offers an outside line of sight range of 10 plus miles and an indoor range of 1 500 plus feet easily pene trating walls Key features include 128 bit AES encryption sub block error detection and retransmission and automatic scan or manual override for the best of 12 communication channels It also fea tures indicator LEDs for channel selection and signal strength point to multipoint configurations with up to 16 subscriber units and up to 12 access points per site to provide a total of 192 points User configuration is via an internal web page Please contact Banner Engineering for pricing Banner Engineering www bannerengineeri
109. hat generates the next 10 round keys yas pe DIF The first operation in the loop rotates a 32 bit quantity right by eight bit posi tions Many 32 bit machines support this operation as it is useful for parsing text strings This is followed by applying Listing 6 The full algorithms for encryp tion and decryption are simple The basic operations are applied repeatedly using a different round key for each round begin encrypt AddKey 0 for i l SubByte ShiftRow MixColumn AddKey i end 1 lt 10 i begin SubByte ShiftRow AddKey 10 end encrypt begin decrypt AddKey 10 for i 9 1 gt 0 InvShiftRow InvSubByte AddKey i InvMi xColumn end i begin InvShiftRow InvSubByte AddKey 0 end decrypt CIRCUIT CELLAR www circuitcellar com Listing 7 The key expansion algorithm operates on 52 bit words It seems to have been optimized for a software implementation begin keyexpand work 0 Key 31 0 work 1 Key 63 327 work 2 Key 95 64 work 3 KeyL127 96 RoundKey 0 work 3 work 2 work 1 work 0 for i l temp temp temp i 11 i begin work 4 i 1 sbox temp temp temp roundCon i temp temp work 4 i 4 work 4 i temp temp temp work 4 i 1 temp temp work 4 i 2 temp temp work 4 i 3 work 4 i 2 temp work 4 i 2 temp work 4 i 1 temp temp 23 0 temp 31 24 j RoundKey i work 4 i 3 work 4 i 2 work 4 i
110. have received thousands of valuable development tools and product samples Because of their contest participation these engineers receive advance e mail notice from Circuit Cellar as soon as new samples become Looking For an Engineer What better place to post your recruitment ad than in Circuit Cellar We are the magazine written by engineers for engineers For information please call or e mail Peter Wostrel strategic Media Marketing Inc 800 454 3741 978 281 7708 peter smmarketing us Phone 719 520 5323 Fax 719 520 1867 Box 60039 Colorado Springs CO 80960 BASIC Compilers for PlCmicro Easy TIo Use BASIC Commands Windows 9x Me 2K XP Interface PICBASIC Compiler 99 95 BASIC Stamp 1 Compatible Supports most 14 bit Core PICs Built In Senal Comm Commands PICBASIC PRO Compiler 249 95 32 bit signed variables and math operations supports Microchip PICTO PIC12 PICTA PICT6 PICT and PIC18 microcontrollers Direct Access to Internal Registers supports In Line Assembly Language Interrupts in PICBASIC and Assembly Built in USB I2C RS 232 and More Source Level Debugging E E See our full range of products including books accessories and components at www melabs com available Now you too can benetit from this early notification Linux Driver LL ME Guaranteed in stock Many newly added features 16 bit analog inputs and outputs Million sample FIFO eliminates interrupts Wi
111. he output expo nent is expl exp2 128 Otherwise the second bit of the product will be set since the product of the mantissas must be greater than or equal to 0 25 and the output mantissa is the top 9 bits of the product shifted left 1 bit The output exponent is expl exp2 129 to account for the left shift of the mantis sa And finally the sign of the product is signi xorCsTam2 ADDITION Addition is actually a little more complicated than multiplication If both inputs are zero the sum is zero Then determine which input is bigger which is smaller absolute value by first comparing the exponents and then the mantissas if necessary Next determine the difference in the exponents and shift the smaller input mantissa right by the difference If the exponent difference is greater than eight then just output the bigger input The smaller number does not contribute sig nificant bits If the signs of the inputs are the same add the bigger and shifted February 2010 Issue 235 UN mI February 2010 Issue 235 smaller mantissas The result must be 0 5 lt sum lt 2 0 If the result is greater than one shift the mantissa sum right one bit and increment the bigger input exponent to become the output expo nent The sign is the sign of either input If the signs of the inputs are dif ferent subtract the bigger and shifted smaller mantissas so that the result is always positive The result must be 0 0
112. hes or bus contention The debug ging environment described here uses them for one simple reason they can make life easier With internal tris tates I can run a single bidirectional data bus out to register blocks and they all get an address and respond to commands quite well They re easily scalable in number When you think about it without the tristate bus each new block of registers would require a separate new input on a data read multiplexer which can become cum bersome as it doesn t change its num ber of ports quite so easily as this tris tate bus Most systems need several registers to control a given function so why not group them together I put them into sets of eight If I want another set of eight registers I just plop down another instance of the reg 8pack module I suppose there could have been a register six pack which sounds nice but of course being greedy for more registers in the end I yielded to the fact that eight is a power of two The register block gets three address lines the data bus read write line and a decoded register block select line From continual use and tweaking many features have been added to the basic register block For example the current register N eo Hannibal HyperTerminal 0 09 18 00 00 00 00 46 00 00 00 FF 00 02 00 6D 69 65 60 5C 00 00 JF 00 00 01 56 01 1E ffib 1 ffib 68 Connected 3 34 00 ANSIW 19200 8 N 1 Photo 1 T
113. his is an example of a screenshot of rs252 syscon in action set up for 16 bit address with 8 bit data and quantity fields If the quantity is omitted the previous value is used block is fully parameterized as to data bus width individual register widths 1 bit minimum default contents of the registers at reset and whether each register is R W or read only There is even a provision for setting or clearing the register bits under control of the logic within the fabric of the FPGA This can come in quite handy when single stepping a microcon troller or implementing a hardware breakpoint BREAKING THE MOLD So now that I ve established some useful building blocks for a basic development environment what about this fabled microcontroller design I ve been dreaming of I ll describe something I figured out while implementing the risc16f84 instruction execution engine I m giv ing it that funny name this time to highlight the fact it s not a fully fea tured PICIGF84 microcontroller Its design has been modified so that it s missing some things which are in the standard PIC16F84 microcontroller and it s got some extra growth as well When working to approximate the performance of an existing proces sor design you can choose which level of compatibility is preserved One choose a design that is com pletely bit accurate and cycle accurate in every way It s a lot of work and less fun in my opinion Two choos
114. i Tech C CCS C devices mpi Delphi C Builder Developers Guide for USB HID Visual Basic 6 Peripherals shows you how to make devices for special requirements HIDmaker FS Combo Only 599 95 www TraceSystemsinc com 301 262 0300 CIRCUIT CELLAR www circuitcellar com NDEX OF ADVERTISERS The Index of Advertisers with links to their web sites is located at www circuitcellar com under the current issue Page Page Page Page 75 AAG Electronica LLC 40 41 Elektor 76 78 JKmicrosystems Inc 45 Nurve Networks LLC 9 AP Circuits 73 Elektor 31 Jameco 34 PCB Pool 78 All Electronics Corp 58 Embedded Developer 23 Jeffrey Kerr LLC C4 Parallax Inc 76 Apex Embedded Systems 20 ExpressPCB 65 Keil Software 77 Phytec America LLC 21 CTIA Wireless 2010 Event 19 ezPCB 77 Keterex Inc 39 PoLabs 33 CWAV 75 FlexiPanel Ltd 14 LPKF Laser amp Electronics 27 Pololu Corp 9 Calao Systems 12 Grid Connect Inc 45 Lakeview Research 77 Reach Technology Inc 57 Cleverscope 23 HobbyLab LLC 76 Lawicel AB 29 Saelig Company 42 Comfile Technology Inc 78 2CChip 5 Lemos International Co Inc 18 19 Technologic Systems 78 Custom Computer Services Inc 49 50 ICbank Inc 11 Linx Technologies Inc 75 Technological Arts 75 Decade Engineering 22 PC APEX Expo 77 MCC Micro Computer Control 77 Tern Inc 32 DesignCon 77 magecraft Creations Inc 77 Maxbotix Inc 15 Texas Instruments 23 DesignNotes 1 Imagineering Inc 76 microEngineering
115. in invmixcol invmixcol inp end endfunction is just an exclusive OR across all 128 bits I show it operating in paral lel here but in my CPU implementa tion software is responsible for doing this 32 bits at a time because the round key is in external memory THE FULL SEQUENCE As I mentioned previously the full algorithm for encryption and decryp tion consists of 10 rounds nine of which are identical Listing 6 shows the sequences for both encryption and decryption in pseudo code format If you want to think of it from a hard ware standpoint each operation corre sponds to one clock cycle for a total of 40 clocks for either encryption or decryption in this example For encryption the very first opera tion is the addition of the first round key which is actually the original cipher key This is followed by nine iterations of the three basic operations plus round key addition followed by a truncated final round If you unroll the loop in the encryp tion algorithm and reverse the order of the operations you can then find the buried reverse loop and shorten the decryption algorithm to that shown in Listing 6 The Verilog module posted on the Circuit Cellar FTP site imple ments the algorithm in exactly this way A state machine cycles through 40 states just like the pseudocode This 2 February 2010 Issue 235 mul_Ob CinplL7 0 mul 0d inpL15 8 mul 09 inpL23 16 mul 0e inp 31 24
116. in by 10 dB and duplicate the WWVB AM modulation levels default 26 dB gain A low bit turns the relay on and boosts the gain 10 dB The resulting 36 dB gain corresponds to a voltage ratio of 63 Recall that the flipflop output was a 5 V p square wave attenuated 20 dB into the filter The filter has O dB gain at 60 kHz and the output was attenu ated another 20 dB The LM386 then applies either 26 or 36 dB for an overall gain of 14 or 4 dB at the amplifier output The highest output 4 dB below 5 V is 3 2 V which I chose because the LM386 can drive that level into a 4 O load A 3 2 V sine wave is 1 1 V usy SiV ing an output power just over 300 mW The 10 dB output 14 dB below 5 V is 1 V 350 mV and 30 mW PP RMS Tweak trimpot R15 so the high gain 1 2 00V 2 2 00V ViCi 937 5mV 0 005 V2C1 3 081 V level is 10 dB above the low level Figure 5 shows the modu lator output at the end of a PWM pulse The MOSFET relay introduces 100 us of delay from the digital input plus a few carrier cycles while the LM386 settles at x12 the new level OUTPUT DRIVE A transmitter is only as good as its antenna but all the antenna choices are bad for LF operation in a con fined space Fortunately this transmit ter has a key advantage it s very close to the receiver I ll go into more detail in the next column but a few tips should get you started I m using a ferrite bar antenna to
117. integral electronics Sound Module 14 pin module plays back pre stored audio files from microSD card bedRF Adeunis Novel ambient sensors amp TE accurately measure temp RH USB Serial A complete CP2102 USB serial converter in a DB9 shell 26 Check www sae amp lig cam often for special offers bargains business hints blog etc CGR 101 www saelig com Mention offer SBW RF Testing EMI Tents RWT320 UPSICAP DLP TH1 Above are some of our best selling unique time saving products see our website for 100s more WiFi 910MHz antennas wireless boards LCD display kits Ethernet IO USB RS232 485 USB OTG instant Ethernet serial CAN LINbus USB cables extenders line testers logic analyzers color sensors motion controllers eng software wireless boards SMD adapters I2C adapters GPS loggers automotive testing security dongles video motion detectors crystals oscillators custom switches barcode scanners DSP filters PLCs Remote MP3 players etc FREE Starbucks card with your 50 order February 2010 Issue 235 UJ SILICON UPDATE A Winning Hand Betting on the ARM Cortex M5 by Tom Cantrell Thirty two bit flash MCUs are the hottest game in town The stakes are high but so is the opportunity presented by billions of sockets to fill Top MCU suppliers are placing their bets on ARM Cortex M5 and putting their chips of the silicon variety naturally on the tab
118. interface for the test circuit First install Visu al Basic and HIDComm Active Control on the PC Two download the attached firmware to a PIC18F4550 and construct the interface circuit Three attach the device to the host and make sure that the PC recognizes it It will show up in the Hardware manager under the HID category as USB LPT Converter In the VB environ ment place a copy of the HIDComm on the form see Photo 2 Define the USB LPT interface to be the device the HIDComm communicates with by choosing Microchip to be the Match Manufacturer condition One ActiveX control can communicate with only one device at a time Fourth write and run the sample program And finally under normal operating conditions the out put indicating LEDs and input switches should corre spond correctly to the data byte E bep SS LPT CONVERTER rar pigeon Fu irera srir pey Fy rm Fm piim af ful da rick Smee o Eai Fe TR R I Photo 2a This screen shot shows the status of the Convert er in Windows Device Manager b This is an example of the input output VB form in the Con verter control program SERIAL CONTROL For the serial port lovers I also included a Microchip project that converts a USB port into a virtual serial port I adapted the serial converter circuit from the original USB development board so that it can work as a standalone module see Figure 4 When the converter module is plugged into the USB port the
119. ion both NXP and Atmel offer M3 parts that are pin and I O register compatible with PI Control loop on Id and Iq Current control FOC Algorithm generates set points for Id Iq Phase angle and frequency from FOC algonithm Id Iq back to FOC algorithm Figure 2 Field oriented motor control calls for significant computation The Toshiba TMPM570 includes a dedicated Vector Engine that han dles the major tasks in hardware including vector to three phase conversion sensorless i e back EMF speed sensing and proportional integral PI control www circuitcellar com CIRCUIT CELLAR Photo 4 You ve heard of Smart Dust wireless sensor networks right Well now it s Smarter Dust thanks to the 5TM52W which combines a 32 bit M5 flash MCU and IEEE 802 15 4 radio on the same die their existing ARM7 based MCUs MORE BITS LESS WIRES Although a bit late to the game S TMicroelectronics is upping the ante in with a full line card of M3 based MCUs befitting their status as a major global player in the IC business Right now I m playing with their new STM32W an M3 that claims fame with a built in IEEE 802 15 4 radio It s Convert to three phase output EM Phase V conversion 223 Coordinate v Jeowenion NN d M SIN COS Sse ly NUM EX pan interpolation cos Ee L Phase conversion 2 23 BEEN d q AB Convert to Id Iq input from ADC not the f
120. ions in the Presence of Noise Reprinted IEEE 1998 www stanford edu class ee104 shannonpaper pdf J Pearce What s All This Eb NNo Stuff Anyway Spread Spectrum Scene Online 2000 www sss mag com ebnO html R Yates A Coding Theory Tutorial Digital Signal Labs 2009 www digitalsignallabs com tutorial pdf J H Yuen and Q D Vo Tn search of a 2 dB coding gain TDA Progress Report 42 83 NASA 1985 http tmo jpl nasa gov progress report 42 83 83C PDF S OURCE SciLab www SciLab org February 2010 Issue 235 67 February 2010 Issue 235 e Qo ROM THE BENCH by Jeff Bachiochi Sun Tracker Part 1 Create a Directional Light Sensor You can check your watch cell phone or the Internet for the time But if you want a more interesting time keeping device try building a sun tracker That s right You can tell the time with the sun and a directional light sensor The sun s readily available you just need to build an efficient system around an MCU and light sensors ne of the greatest advantages to working from home is the freedom to take a break at any time and actually get outside during daylight hours And I can t think of a better place to view Mother Nature in all her grandeur than New England where I live There is something special about experiencing a new season every three months Last spring on a Boy Scouts of America BSA camp out the sched ule inc
121. irst chip to combine an MCU and a radio But where earlier devices might have used an 8 bit MCU or a multi die system in package the 32W integrates the M3 MCU and radio on the same die Without dissecting the rationale for single die multiple die in a single chip and multi chip solutions a nontrivial discussion let s just say that if you want a 32 bit MCU and radio on a single piece of silicon the Duty cycle outputs to PMD Unit Three phase PWM Output settings PMD Sync trigger settings PMD Input rocessin P g Current voltage detection ADC Shunt readings February 2010 Issue 235 UJ Q February 2010 Issue 235 LEk Fie View Capture Protocols Filters Settings Window Help Products from Daintree Networks S a bel Source COME Generic Protocol Version 4 SD Channel 26 0x14 2480 MHz r Replay 1 J e E amp Visual Device T a3 ZI EE Packet Decode View Network jg iy gt Bg Frame 17 Length 27 octets Sensor Network Analyzer lt COM6 Generic Protocol Version 4 0x0000 00 80 61 02 00 00 00 5a Sequence Number 17 Device Coordinator Time Stamp Wed 14 Oct 09 05 42 41 060 Time Delta 00 00 00 003 Frame Length 27 octets Capture Length 27 octets Link Quality Indication 189 FCS Correct 0x01 Protocol IEEE 802 15 4 Packet Type Command Association Response IEEE 802 15 4 Association Response Short Address
122. issa one for the sign and eight for the exponent This format gives a numerical range of about 10 Any number smaller than about 10 underflows to zero The resolution of the mantissa is only about 0 002 but this relatively low reso lution is high enough for a range of DSP applications Also a 9 bit mantissa allowed me to use just one hardware multiplier The mantissa is an unsigned fraction with the radix point just to the left of the top digit so the maximum fraction is 1 2 I made the decision not to support denormalized fractions so the minimum fraction is 0 5 with just the high order bit of the mantissa set If the number underflows then the man tissa is set to zero The sign bit is zero if the number is positive The exponent is represented in 8 bit offset binary form For example 2 is represented as Oh80 2 as Oh82 and 2 as Oh7f The Verilog representation for the 18 bit format is sign exp 7 0 mantissa 8 0 I did not implement the special numerical values available in IEEE 754 NANSs infinities denorms so no bit patterns were allocated for these values A few mantissa 0h100 0h100 0h100 0h140 0h199 CIRCUIT CELLAR www circuitcellar com Listing 1 This is code for the floating multiplier MIETT MT MP MB M MMC TITS STITT ALALLA LLL floating point multiply Sign bit 8 bit exponent 9 bit mantissa NO denorms no flags no NAN no infinity no rounding PHI T T MTEIDAH4YYA
123. isting individ ually and then I ll put everything together later for the full AES algorithm The first operation is a byte wise substitution that the AES standard calls SubBytes or S Box In this opera tion each individual byte is replaced by another byte using the table look up in Listing 2 Remember that data can not be destroyed so each input byte maps one to one to a different output byte This is an affine transformation The standard provides the mathe matical basis for this transformation but admits that expressing it in terms Nn eo 4 b0000 msb sbox 4 b0001 4 b0010 4 b0011 4 b0100 4 b0101 4 b0110 4 b0111 4 b1000 4 b1001 4 b1010 4 b1011 4 b1100 4 b1101 4 b1110 4 b1111 msb_sbox msb_sbox msb_sbox msb_sbox msb_sbox msb_sbox msb_sbox msb sbox msb sbox msb sbox msb sbox msb sbox msb sbox msb sbox msb sbox 128 h637c777bf26b6fc53001672bfed7ab76 128 hca82c97 dfab5947f0add4a2af9ca472c0 128 hb7fd9326363ff7cc34a5e5f171d83115 128 h04c723c31896059a071280e2eb27b275 128 h09832c1alb6e5aa0523bd6b329e32f84 128 h53d100ed20fcbl5b6acbbe394a4cb8cf 128 hd0efaafb4344d338545f9027f503c9fa88 128 h51a3408f929d38fb5bbcb6da2110fff342 128 hcd0c13ec5f974417c4a77e3d645d1973 128 heo0814fdc222a908846eeb814debeObdb 128 he0323a0a4906245cc2d3ac629195e479 128 he7 c837 6d8dd54ea96cb56f4ea65 aae08 128 hba7 8252e1ca6b4c 6e8dd741f4bbd8b8a 128 h703eb5664803f60e613557b986c11d9e 128 helf8
124. itical A few hundred ohms would be enough to avoid a short circuit Figure 3 depicts the functional compatibility of the USB parallel interface and the conventional Parallel printer port in parallel port control applications I posted both the circuit printer port control program and the USB control program per forming the same function to illustrate how easy it is to migrate from one to the other Both programs control LEDs and monitor input states of switches Printer Generally depending on the LPT cable number N N and N 2 are output ports and N 1 is the input port in printer port control applications Similarly I define 1 and 3 in the USB case to be the output ports port D and port B in the PICIS8F4550 and 2 the Interface Figure 3 Michael Figure 5 This pictorial diagram illustrates two alternate schemes for a host input port portA The data after computer to communicate with a parallel port control device via either the printer or the U5B the port identification number port are the control bytes representing WWW circuitcellar com CIRCUIT CELLAR DONUS V February 2010 Issue 235 CIRCUIT CELLAR DIGITAL PLUS BONUS LED Switch states A word of caution it is important to remember that some of the printer port bits are inverted Therefore take care of them accordingly in the control byte value Listing 3 shows the control programs Let s review the proce dures for using the USB LPT
125. kkkkkkkkkkkkkkkkkkkkkkkxkkxk z register next input tf KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKE always aluop_reg or w_reg or x_reg or y_reg or z_reg or key_reg begin casex aluop_reg AOP_SBOX z_reg_nxt sbox z_reg 31 24 sbox z_reg 23 16 sbox z_regl15 81 sbox z_regl 0 AOP_ISBOX z reg nxt ibox z_reg 31 24 ibox z reg 23 16 ibox z reg 15 8 ibox z_reg 7 0 ET AO0P SHROW z reg nxt y reg 31 24 x reg 23 16 w reg 15 8 z_reg 0 em AOP ISHROW z reg nxt w reg 31 24 x reg 23 16 y reg 15 8 z reg 7 01 5 S AOP_MXCOL z_reg_nxt mixcol z reg 2 AOP_IMXCOL z reg nxt invmixcol z reg AOP_ADDKEY z_reg_nxt z_reg key_reg 127 96 em default z neg nxt z reg S endcase e end E el 5 x 55 www circuitcellar com CIRCUIT CELLAR of the bytes without the normal carry between bits And remember that XOR ing a bit with itself always results in a zero which serves to remove that bit from contributing to the result This fact is important because this is what allows the decryption operations to be UE is as simple as those used for the original reg 127 0 msb sbox encryption With this background infor begin Listing 2 The byte substitution is most easily specified using a look up table This could be implemented as a small ROM but a logic synthesis tool will minimize the logic into something quite s
126. l to Ethernet Development Kits are available to customize any aspect of operation including web pages data filtering or custom network applications All kits include platform hardware ANSI C C compiler TCP IP stack web server e mail protocols RTOS flash file system Eclipse IDE debugger cables and power supply The NetBurner Security Suite option includes SSH v1 amp v2 support etBurner Networking in One Day Information and Sales sales netburner com Web www netburner com Telephone 1 800 695 6828 freescale Alliance Member Overseas Manufacturing Imagineering Inc enjoys the reputation of being one of the most experienced amp successful offshore PCB suppliers CAM USA Our Illinois based DFM office has eight fully staffed CAD CAM stations Within hours of receipt of new Gerber files our highly experienced DFM engineers conduct thorough and precise analyses Quick Turn Production Imagineering offers small volume production in 5 6 days and medium to large volume production in 2 3 weeks Overseas Manufacturing Shipping Logistics With Imagineering there is no need to deal with multiple suppliers language barriers customs headaches and shipping logistics We do it all for you and deliver door to door Significant Price Saving Our global buy ing power c with the capabilities of manufacturers translate into tremendous savings to our custo
127. lass e Small form factor Low pin count Expanded serial connectivity Whiteout class e Small form factor Low pin count 2011 Figure 1 The letterhead may be different it now says TI instead of Luminary but the Stellaris family continues to grow The most recent addition is the 9000 line of Tempest Class MCUs to be followed by both higher and lower end parts CIRCUIT CELLAR www circuitcellar com What is the missing component ici M PF 03 r M lies a A t g ne ue ES Les ie a ae d er i nk ne Lx L H E e E u F War Ev Y Ad es i 4 k E L Til Y i a I m rm i 4 P t Iu LV NI ar die E P s a 4 n d Sees T M s zuo x ZU cat NL E 1 po ELECTRONICS Bridging The Gap TS 1 800 831 4247 PME ele elo February 2010 Issue 235 have hopped on the bandwagon one by fence sitters went ahead and signed up bought them as the most expeditious one as well Luminary did such a good job way to get their own piece of the M3 There s no better way to reinforce that Texas Instruments TT recently action the point than to take a look at new Cortex M3 MCUS from a premier global supply chain a who s who of six count em major players LIGHTING THE WA There s a good PA I wouldn t be writing this article at least not yet if it wasn t for Luminary Micro Recall that when ARM first announced the move t
128. le ongtime readers know I ve been a stalwart defender of 8 bit MCUs I can t count how many times over the years some pundit has read their eulogies Of course all the while our little friends continue to ship billions of units a year and they will for many years to come to fill a backlog of evermore global demand But at the same time there s no doubt that 32 bit MCUS are hitting their stride And when it comes to 32 bit MCUs nobody DustDevil class e 128 KB Flash memory 64 KB SRAM Motion control Fury class enhancements e 256 KB Flash e USB 2 0 O H D memory e 32 Channel DMA 64 KB SRAM Motion control EE ETH MAC PHY 64 ash e CAN 2 0 meme e Ethernet CAN e 8 KB SRAM e Motion control e 1 MSPS ADC holds a better hand than ARM They ve lever aged an open business model and the know how of heavyweight chip partners to finesse their way through architectural hoops that might have tripped up a lesser contender I ll admit I had some doubts about the transi tion from the historic ARM7 9 11 lineup to the new Cortex regime But in the case of their microcontroller offering Cortex M3 those doubts have been erased as major MCU suppliers Tempest class Higher performance Low power ETH CAN USB OTG External bus capability e S Precision oscillator Brainstorm class Advanced analog 1 024 KB Flash memory Firestorm class Advanced analog e 512 KB Flash memory Blizzard c
129. le program to draw my schematics and lay out my PCBs Most discrete parts are found in the sup ported libraries The Download section at www cadsoftusa com has a library folder for sharing user designed parts libraries To produce a sensor module PCB I began by creating a schematic drawing of the circuit The resistors capacitors and pin header used in Figure 1 are already in the standard libraries but I needed to add the ISL29102 to my private library This required three steps First you create a picture of the part including all of the labeled connections to the device that s used on the schematic drawing Second you create a PCB layout format containing either through hole pads or SMT pads These are drawn to scale using the dimensional information supplied on a part s datasheet Many parts come in different standard package styles Your new part may already have a PCB layout format that you can borrow from another part The last step involves matching your schematic picture s connections to the actual PCB layout pins for all of the part s package styles This enables the connections you make on a schematic draw ing nets to be transformed into connections required between the actual parts on the PCB LAYOUT When the schematic drawing is completed Eagle has enough information to help create a PCB layout The layout application begins with a standard sized PCB outline and parts pulled from your schematic At this point
130. legeprogram Vg s i ds sog E Ta P 3 10Base T Ethernet TM 186 Processor amp 40 MHz DOS wi Flash File System 16 Digital I D 5V DC Mel zs Console Debug Port 2 Serial Ports Hardware Clock Calendar 2 16 bit Timers Socket for DiskOnChip Watchdog Timer 512K DRAM amp 512K Flash 3 75 x 2 50 Embedded Ethernet picoFlash Controller Borland C C 4 52 gt TCP IP PPP amp Web Server Serial Driver Library AC Adapter and Cables Call 530 297 6073 Email sales amp jkmicro com On the web at www jkmicro com CCS Wireless Ember ZigBee Edition Base Station PIC18LF4620 2 Sensor Boards PICI6LF886 Full commnunication Protocals with Ember ZigBee stack 1 Sere itty eT ae cmo eo de mp Qo February 2010 Issue 935 m The PLC with everything you ever wished for Lead the Green Revolution with our Smart Buildings control model Tri Triangle Research International Ine From the Programmable Logic Controller specialists who brought you the Super M serres NOW 1 The Ultimate F series 12 Relay Oufputs 24VAC DC or 250VAC Infra Red Remote Control OEM Prices A V equipment control Us EIE below 400 ee ele el 1x RS232 2x RS485 12 Analog I Os 12 bit O 10V 4 Super Outputs PWM Steppers Light dimmer ETHERNET Modbus TCP id s YT TL y e Internet Programming Emails PLC
131. ler sockets T Cantrell In ARM s Way Circuit Cellar 158 2003 It s no surprise that NXP and Atmel are still See It amp Solve It the driving forces today with catalogs with chock full of practical ARM7 and USBee Test Pods ARM workhorses from 1 to 10 and Logic Analyzers Configurable Oscilloscopes Programmable tens to hundreds of MIPS And now Signal Generators High Speed USB they re rolling out M3s Protocol Analyzers PC Based e 2C SPI ASYNC CAN e And start at 139 NXP offers two distinct M3 based product lines the LPC1300 and LPC1700 The range between the two is testimony to the vast application 1 Wire P5 2 USB 25 SMBus Serial z El www USBee com USB based Electrical Engineer www circuitcellar com CIRCUIT CELLAR e February 2010 Issue 235 for virtually any application There s a 10 100 Ethernet MAC CAN USB 2 0 full speed host device UART SPI PC PWM RTC ADC DAC and the list goes on It s has everything and then some more megahertz up to 100 more memory up to 512 KB flash memory 64 KB RAM more pins 80 to 100 and more than enough I O 3 D Accelerometer Sensor IZ bit High Speed d Input 0 bit Low power ADC Input Potentioneter Photo 3 Kitchen sink MCUs like the Atmel SAM3U have so many I O features that it takes a lot of evalua tion board to support a single chip THE ORIGINAL SINCE PCB PNAL Beta LAYOUT 9 e Lo
132. ll As you may have guessed the monitor hard ware will have a super short learning curve which is really not a bad deal Once it has met its purpose it can be cut out of the design completely if desired IP CORES This article focuses on producing complex FPGA designs from basic building blocks that were written from scratch This presents a paradox of sorts How do I effectively share what I ve already built up while at the same time encourage the sort of deep learn ing that comes from building a set of code modules from scratch In essence what I ve decided is that most design ers want to build a particular new func tion and would rather not have to reinvent the wheel for all the sur rounding support logic needed to exer cise the experimental new module Enter the firmware based design and RS232 syscon Syntax debugging environ ment built around a homemade IP core called rs232 syscon see Photo 1 It works through a serial port with no software need ed and it allows you to enter and read back parallel data from reg isters and memory as well as initiate a Reset command With user defined register fields for go single step and for setting hard ware breakpoints there is really no limit to what the digital or DSP designer can define debug and use with such a system Although it is tedious to hand enter large amounts of data through the hyperterm driven inter face scripts can b
133. ll size the chip has a decent com a 150 MBps machine to machine The LPC1300 is a little socket rock plement of I O and glue logic i e like mode that seems ideal for high speed et cramming M3 horsepower into tiny you d typically find on 8 bit MCU in a chip to chip connections such as with 33 and 44 pin packages Sure the gas similar package and it even includes a another processor or an FPGA see tank is small up to 32 KB flash mem full speed USB device interface Photo 1 ory and 8 KB RAM but the 1300 is At the other end of the spectrum is At the other end of the lineup recall really quick stoplight to stoplight the LPC1700 It s one of those amazing ing the buzz Luminary generated with with 70 MHz on tap and it burns just kitchen sink microcontrollers that their 1 price breakthrough entry level parts e g the LM3S1Z16 with 16 KB of flash and 6 KB of SRAM now have a tiny 7 x 7 mm 44 pin QFN package option joining the original s LOFP IN THE BEGINNING These days ARM sings the praises of the mass market MCU But it wasn t always so Between their computer heritage and infatuation with cell phones I wondered for a long time if they would ever get it Now they do thanks largely to the pioneering efforts of NXP then Philips Semiconductors and Atmel In the early part of the decade these outfits pioneered the concept of putting an ARM computer to work in con trol
134. lly consists of a pulsed transmitter receiver The reader s transmitter pro duces enough RF energy at a specific fre quency Thus when a matching RFID tag comes into proximity the tag s antenna extracts enough energy from this RF field to charge a small capacitor inside it The stored energy is then used DOWNLOAD our free CAD software DESIGN your two or four layer PC board SEND us your design with just a click RECEIVE top quality boards in just days expresspcb com N to power a small microcontroller in the tag which either sends back a short burst of RF energy or modulates the reader s own transmitted signal by shorting out its own antenna In either case the modulated RF field is encoded with a pattern that s unique to that particular tag The reader decodes this ID information and sends it as a message to an external microcontroller usually via a serial data link The most common RFID tags the so called low frequency LF tags operate at 125 kHz ISO14443 high frequency HF cards operate at 13 56 MHz All things being equal the HF tags would require a much smaller antenna which is advantageous if one needs physically smaller tags Also due to the higher car rier frequency the HF tags can transmit much more information in a given amount of time which is beneficial in some applications Therefore LF tags are often used when all that is needed is a unique ID code per tag frequently a uni
135. loating point hardware from scratch helps my understanding and teach ing Also I was able to fit the algo rithms more closely to the architecture of the Altera Corp Cyclone II FPGAs we use at Cornell to teach the course titled Advanced Microcontroller Design ECE5760 The close fit to the architecture makes it possible to instantiate up to 70 floating point multipliers on the Cyclone II which ships with the Altera Terasic educa tional DE2 prototype board When we use the full IEEE floating point multi plier from Altera we can fit only three multipliers on the FPGA we use sign Oh84 Figure 1 These are decimal values and their floating format equivalents B e ex p Oh80 Oh80 Oh82 Finally narrow floating point formats have been shown to be quite useful for DSP applications where IEEE 754 is overkill 25 5 To implement a floating point system you need to pick a floating point representation and execute five basic opera tions necessary to use floating point for DSP and other fine grained parallel operations You need to be able to add mul tiply and negate and because audio and video codecs require fixed point integers you need to convert integer to float and float to integer IMPLEMENT FLOATING POINT I decided to use 18 bit numbers because 18 bits is a native width for Altera s M4K memory blocks and can be read or written in one clock cycle Of those 18 bits nine are used for the mant
136. luded an afternoon of orienteering which included map and compass work Understanding how to use a compass is an important skill but being able to orient yourself without one can be just as important You can use the sun by day and the North Star by night at least in the Northern Hemisphere The shadow stick method uses the movement of a shadow over time to draw a line from the west toward the east If you have a watch or at least know the time you can use the analog time compass method While you need to see the sun to use both methods it s always comforting to know that you can figure out which way is up or north if necessary Research shows that the ancient Egyptians first used shadow clocks to divide the day into time periods However cloudy days provided the impe tus to find other ways of keeping time Although the first sign of using dripping water as a clock was found in a pharaoh s tomb the Chinese took the use of water to new level with an astronomi cal astrological clock Not much changed until sometime around the 14 century when the weight driven clock became regulated with a verge and foliot escapement Springs then replaced weights and later crystals replaced springs And now today many clocks don t have gears or hands We live in the digital world Still there is some thing divine in the simplicity of the sundial While many sundials use a shadow to point to the present hour s digit one of my favorite
137. ly The connections were provided by an IDC cable see Photo 2 You can review FiPololu Robotics amp Electronics Robot Kits Line followers Robot arms High Sanana C programmable ATmega328P based robot with Arduino support items 975 1306 Mechanical Components E Mo Kors servos a Whe 5 ball casters oe Motion Control otor controllers Soc pontrollers r e a pay t r i s P mg connector 20 MHz clock Solder Paste Stencils Use our low cost solder page stencils From 25 Seen Pee BERR eS EE E Cut your own custon chassis front panels and more 1 877 7 POLOLU www pololu com 3095 E Patrick Ln 12 Las Vegas NV 89120 February 2010 Issue 235 21 February 2010 Issue 235 y ian 0 TS ui i alki Baete a2 Photo 2a This is the FPGA breakout board There is a ribbon cable connection to the WlZnet board The USB is only for power The interface to rs232_syscon is via a nine pin D shell connector b This view from the back shows the Xilinx FPGA configuration PROM and an on board parallel cable implementation my flexible audio transmission over Ethernet FATE project at www circuit cellar com Wiznet winners 001 103 html The design sets up a simple dedicated wired Ethernet network You can then use the network to coordinate the dis tribution of high quality audio signals thro
138. mall RK KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK aes sbox RKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK case byte 7 4 February 2010 Issue 235 mation in mind let s go over the basic operations used for encryption FOUR BASIC OPERATIONS For what follows assume that the data to be encrypted is held in the four 32 bit registers in Figure 1 and that each operation is applied to all four registers in parallel Also assume the entire 128 bit round key is available in another register This is very close to what I ended up with in my CPU design It s actually the Rabbit 6000 This design uses one clock cycle per operation attempting to balance the amount of logic required against time Different trade offs are certainly possi ble At one extreme it is possible to perform the entire encryption or decryption process in one clock cycle with each round implemented as a few of layers of logic The other extreme is operating on one byte at a time minimizing the logic but requir ing significantly more time For exam ple this would be the case when imple menting the algorithm on an 8 bit microprocessor in software My intent here is to provide a useful starting point even if your implementation will be in software Listing 1 shows how the 128 bits of data in the four registers are modified by each operation Let s start by looking at each operation in the l
139. mation PROTECT YOUR DATA For all of its power the AES algo rithm is fairly easy to understand once the individual operations are clear However the AES specifies the opera tions with mathematical rigor which obscures what is going on during the encryption decryption process Hope fully I ve made the encryption decryp tion process a little clearer and now you can be confident that your data really is protected l Monte Dalrymple monted systemyde com has been designing integrated cir cuits for over 30 years He holds a BSEE and an MSEE from the University of California at Berkeley and has 15 patents Monte designed all five generations of Rabbit microprocessors Not limited to things digital he holds both amateur and commercial radio licenses P rosea FILES To download the code go to ftp ftp circuitcellar com pub Circuit_Cellar 2010 235 Bo NIST Announcing the Advanced Encryption Standard Federal Information Processing Standards Publication 197 2001 www csrc nist gov publications fips fips197 fips 197 pdf A February 2010 Issue 235 February 2010 Issue 235 e N pt DARKER SIDE by Robert Lacoste Living with Errors An Introduction to Forward Error Correction Forward error correction FEC algorithms are commonly used in disk encoding RAM chips GSM mobile phones and more But what is FEC This article int roduces the topic of FEC and Hamming FEC encoding
140. mers Over the past 5 years 70 000 protdtypes have been successfully delivered from overseas to over 5000 customers our overse F E a 2 NP 4 Pi o IE SEI Yo a A ZR CU D T ux LS i 2 a E BEP ce T vr rec eI ics Boor to Door Delivery Sig ificant Price Saving DF E Ee M w DLE D 9 hdi D E IA 2 3223237252522 i aala aaa ayaa arr ISP rw TP y Foa 33 halala 2 22 gt vw a as AAW E boh B ee ee ee ee ee 5 pg 3 JAN 725 3 A2 EAS Capabilities Up to 30 Layers Blind Buried Vias Di Electric Thickness Paet L Impedance Control TDR Tested Plated ed Edge Holes Upto 6oz Copper o mil Taser ril 9 MINE wWaNSpacINg Gonauctive ele ey millsel MES mricioniioition jj site Clejc gt Boards and many others m 151102226081 54 ftoi ied inh 24 h ea V ER voc pe MILI ud FN BL rm ete i linc 28 B VP EL 005 www BO Biet com email sales PCBnet com 23 YEARS IN BUSINESS AND STILL GOING STRONG atid DESIGN CONTEST the Your creativity and design project idea could win you a share of in Cash Prizes and Recognition in Circuit Cellar magazine For details visit zA FUTURE ZA ELECTRONICS IMCU7100EVB Contest Special Price 49 00 USD Co sponsor Official Sample Purchase www FutureElectronics com
141. micro com www jkmicro com JK microsystems Inc International Orders Welcome UJ N DESIGNGON Fo The BRIGHTEST Minds in Electronic Design February 1 4 2010 February 2 3 2010 Santa Clara Convention Center Santa Clara California DesignCon Be a Chiphead to the DesignCon registration counters to receive your complimentary www designcon com 2010 CIRCUIT CELLAR www circuitcellar com With the TI brand manufacturing capability and balance sheet backing their hand it s onward and upward for Axe o ARM tbed module subici obl Hes the Stellaris roadmap see Figure 1 A Y x A Ese Roe d rds and Unc with the recent release of dozens of a eS Vl T N cloud computing web based tools new parts At the high end the new C X 9000 series aka Tempest Class with 256 KB flash memory and 64 KB SRAM covers home USB 2 0 full speed factory CAN 2 0 and office 10 100 Ethernet MAC and PHY apps with one chip that does it all The 9000 series parts also include software in ROM that goes beyond the typical bootloader to include things like peripheral USB and graphics drivers I don t have the details yet but this is an interesting feature worthy of further exploration The 9000 series also hasa opportunity for 32 bit flash memory 200 pA MHz along the way Despite its Photo 2 The first NXP M3 MCU the LPC1768 makes its debut in the high speed external bus interface with MCUs sma
142. ml Pick a Chip Any Chip Find a Solution to your next Embedded Challenge Do the Research you should but never had time for Embedded Developer s intuitive research engine gssisssuss oc DEM f d anyan sag e Any Core Architecture helps you speed your chip i aa M 17 evaluation time You don t have m pea B Encryption to know the manufacturer chip Wires I taa IL internal Oscillator family or part number just gi i anyuss A n oto select the features you want and let us do the rest E We help you research your best option Nowhere else can you compare your best options side by side from different Core Variant ARM TDMI ColdFire V ee a In UNE ene and a product page lets you selec ere te Distributor Buy Quote options send RFQs download datasheets and more Plus Hearst stock check gives you up to date inventory on every device Once you have the chip that meets your needs review and compare the hardware and software RTOS ICE Eval Board development tools that support it from multiple manufacturers and buy them on line through our shopping cart V 12C CAN Ethernet NO Qus PCI DDR etc Shave days off your schedule with Embedded Developer the only site in the world where youre only clicks away from finding the chips and tools to get you up and running quickly Try EmbeddedDeveloper com or EmbeddedDeveloper cn in Chinese FMBEO
143. more weakly than the oth ers and these bits will have a higher probability to be erroneous The Viterbi algorithm can use this information to improve its performance statistically This is the family of soft decision decoders The list of convolutional FEC codes didn t stop with the basic Viterbi algo rithm The latest and greatest are proba bly turbo codes which were invented in the early 1990s by two French researchers Claude Berrou and Alain Glavieux trom the ENST Bretagne engineering school and France Telecom The invention which won the IEEE Richard W Hamming Medal in 2003 performs within 1 dB of Shannon s BER over Eb No Hamming 15 11 EB No dB Figure 8 5witching to longer codes Hamming 15 11 in this instance provides a significantly better improvement up to CIRCUIT CELLAR www circuitcellar com limit thanks to the use of composite codes Turbo codes are used in all recent space projects but also in the 3GPP UMTS and WIMAX wireless standards Who is next Input bit stream TUI UL FEC EXPERIMENTATION All error correction codes provide a BER over E N curve more or less close to those shown in this article For a high noise level i e for low signal over noise ratios the code can t help and it can even degrade the reception due to the higher number of bits to be transmit ted However when the bit error rate is lower i e for better signal over noise ratios the FEC cod
144. mpact Panel PC with a 4 3 inch WQVGA 480 x 272 TFT color LCD and a resistive touch screen The dimensions of the PPC E4 are 4 8 by 3 0 about the same dimensions as that of popular touch cell phones The PPC E4 is small enough to fit in a 2U rack enclosure Price is 345 at quantity 1 Min Volume Discounts For more info visit www emacinc com panel_pc ppc_e4 htm Available since 1985 CS 7 2 EMA gt NC iz gridconnect EU MM Motos Ea i 1 800 975 4743 Phone 618 529 4525 e Fax 618 457 0110 www emacinc com EN N CIRCUIT CELLAR e www circuitcellar com HIGH PERFORMANCE SMALL FOOTPRINT DEVELOPMENT BOARD The Chameleon is the next step in the evolution of the high perform ance small footprint application development board It is a credit card sized computer with two processors nine processing cores 1 MB of on board flash memory and 64 KB of EEPROM It also includes numerous I O interfaces that include composite video for NTSC PAL VGA audio out P5 2 for keyboards and mice Additionally it has a number of digital Os and analog inputs The power of the Chameleon is in its dual processor design It is avail able in two flavors an AVR 8 bit version and a FIC 16 bit version The AVR version uses the Atmel AVR528PF processor while the PIC version uses the Microchip Technology FIC24 as the main master processor client along with the multicore Propeller chip as the media processor
145. n tation which are columns in the stan dard Mi xColumn replaces each byte in a register with a unique combination of all 4 bytes of the register The replacement values are made unique by two of the operations shown in Listing 4 called mul 02 and mul 03 If you re interested this is how multi plication is defined for the math used in the AES standard Multiplying a byte by two is the basic operation from which all of the other transformations are cre ated Multiplying by two involves a rotate left plus the conditional inver sion of three of the resultant bits as shown in the mul 02 function All of the other multiply operations shown in Listing 4 can be built up from this basic definition along with addi tion but for our purposes they are just byte scrambling functions These trans formations could be specified in table form like the sbox and ibox functions but I find this XOR version easier to understand The exact combinations of transformations used for each byte are shown in Listing 5 Like Shi ftRow this operation can be extremely cum bersome to implement in software because both scrambled versions of each byte in a 32 bit word are needed to create the new 32 bit word Even so AES is much easier to implement than the previous Data Encryption Standard DES because at least the operations here are byte aligned The inverse of Mi xColumn is identi cal except that the scrambling func tions are different and
146. n Hartley theorem This theorem is February 2010 Issue 235 fundamental to the FEC dis cussion It says that if you have a transmission channel with a bandwidth B in hertz and a given signal over noise ratio S N then the maximum error free bit rate you can dream of is calculated as C B x log 1 S N Even if you have a powerful error correc tion algorithm or ultra sophisticated modulation sys tem you ll never be able to transmit more data without errors through this transmis sion channel For example if you are developing a wireless system with a 100 kHz wide RF channel and if you have a signal 10 times more powerful than noise then the theoretical maximum error free data throughput will be 100K x log 1 10 345 kbps This would jump to 665 kbps with a SNR of 100 meaning 20 dB but it will be reduced to 13 7 kbps if the sig nal is 10 times lower than noise 10 dB Your goal as an engineer will be to find a way to come as close as possible to this limit but if the requirements are higher you can safely tell your manager No way HAMMING CODE As you can imagine there are plenty of FEC algorithms They are split into two categories Linear block codes work on a fixed length block of data Convolu tional codes manage a continuous stream of bits Let s start with linear block codes The most basic approach to FEC is repe tition Suppose that you have a 3 byte message to send
147. n it comes to deliver ing a robust link budget 100 dBm sensitivity up to 7 dBm output power Better yet the radio hardware working together with the built in DMAC handles many MAC layer functions that would otherwise burden the MCU such as packet filtering acknowledgement and timing CRC generation checking link quality receive signal strength and so on AES acceleration hardware and a true i e thermal noise random number generator facilitate secure applications The radio even gets its own debug sup port with a dedicated packet trace interface that nonintru sively monitors traffic between the MAC and baseband On the software side STMicroelectronics does their best to keep up with ZigBee feature creep particularly with recent moves towards IP interoperability 6GLowPAN and a shotgun marriage with consumer electronics RF4CE The UJ eo latter intends to replace your quiver of IR remote controls e g TV DVD etc with radio versions i e no more point and shoot just shoot However RFACE does have capabilities e g acknowledged transactions that could take it beyond couch potato applications Maybe it has a role to play as kind of a ZigBee Lite with ZigBee PRO having moved onto bigger and ostensibly better things At 200 the STM32W Starter Kit is a decent deal because it comes with a full fledged IAR J Link emulator program mer and three radios to play with see Photo 4 To fully exercise
148. n with making it Perhaps it s genetic don t know But all the engineers l ve ever known will keep adding func tions and features on any product they are creating right up until the last second before it goes to production or management demands a stop to it simply to stay on schedule and budget lm not complaining l m just pointing out an all too observable trait As an engineer who is just as guilty of this as the rest of you simply offer the old Mount Everest defense A climber is asked Why would you climb it He answers Because it s there silly When one of us is asked why we can t stop tweaking the designs we re working on we answer Because we re engineers silly And while readily admit guilt by association it doesn t make me any less sensitive to the frustration of personally having to deal with over tech along with proper feature enhancement Many of you might already know l m a car junkie and that I ve had a vari ety of them over the years I just ordered a diesel to try that too suppose shouldn t complain but since 2001 I ve had a cou ple BMWs in which I ve felt like I ve been driving computers not cars They are still a blast to drive but I m not sure whether feel more or less secure knowing that it s a bunch of processors and programmers responsible for apparently making me such an excellent driver It used to be that I d have to take an entrance ramp with reasonable caution But now with computerized
149. n with the standard ShiftRow leaves the least signifi cant bytes in each register unchanged but rotates the other bytes between the four registers by one two or three positions The intent here seems to be to scramble 16 or 32 bit values This operation can be cumbersome to implement in software or in hard ware when the parallel operation on all four registers is not possible This is one reason that I chose this particu lar implementation Anything else would require keeping temporary copies of the registers while doing the scrambling The inverse of Shi f tRow is identi cal except that the rotations occur in High Resolution Spectrum Analysis Tracer Chan A M1 Chan A M2 Chan A Time 0 001 s Amplitude 112 3 dB 0 825 dB 0 040 dB deita 0 315 dB Freq 28 59 MHz 1 000 MHz 1 001 MHz delta 0 001 MH aj c LinF Source Scope Divisions A 10 00 dB B 5 000 dB 5 000 MHz I I I I 70 0 80 0 100 0 110 0 7 o Example Capture 1 000 and 1 001 MHz mixed signals Display the signals Intermod is 80 dB PAORA A un chan amp Mz Chan A aa m s impins ar a au E n m e sor a us 10008 Kis TOCA dem TES 0448 ei aena Gre am in the USA call Check out High Resolution Spectrum Analysis on the Examples page at www cleverscope com February 2010 Issue 235 Q
150. ng you premier tradeshows that are on the cutting edge of technology For 25 years CTIA has fostered a dynamic global marketplace and provided an unparalleled venue for industry players of all sizes and influence to showcase their products and services to a high quality buying audience CTIA is proud to present two events a year that celebrate the totality of the wireless experience THE SPRING EVENT THE FALL EVENT MobileUfe Mobile Business Qntemationad c kan WIRELESS 2010 Qntennationad c 7 Te TN ED B ec IT amp E 2010 of CTIA The Wireless Ass A Div of CTIA The Wireless Ass March 23 25 2010 October 6 8 2010 Las Vegas Convention Center Las Vegas NV Moscone Center West San Francisco CA International CTIA WIRELESS is one of the largest International CTIA WIRELESS IT amp E is more niche technology events in the world Encompassing all things and hones in on the application and usage of wireless wireless this show is the essential marketplace for the global technology in any business health energy retail content broadband industries bringing clarity to the present and applications transportation just to name a few insight into the future CTIA s events have long featured prestigious awards fascinating product demonstrations and iconic speakers including some that created the high tech industry and all who have the vision for what Mobile Life and Mobile Business really are and where we can go jonored b
151. ng com DIGITAL PREAMPLIFIER CONTROLLER IC The THAT5171 is a new digital gain controller IC for low trolled audio preamplifiers For designers who prefer a more noise analog differential current feedback audio preampli customized solution the 5171 may be used to control a fiers When used in conjunction with an appropriate analog discrete preamplifier To reduce zipper noise in audio appli gain block the 5171 can set gain in 1 dB steps while preserv cations the 5171 includes a differential servo and zero ing low noise and distortion crossing detector to minimize DC offsets and glitches during The 5171 operates from 5 V to x17 V supplies and sup gain adjustments ports input signal levels as high as 22 dBu at 5 6 dB gain and 17 V supplies with gain error guaranteed at O 5 dB maximum at all gain settings Applica tions for the 5171 include digitally con trolled instrumentation amplifiers digi tally controlled differential amplifiers and a variety of digitally controlled audio instrumentation The 5171 mates with the THAT1570 differential audio preamplifier IC for a best in class solution for digitally con The 5171 is controlled via an addressable SPI port Four general pur pose digital outputs can be controlled via this interface The SPI bus supports read back so that host software can verify proper operation The THAT5171 comes in a 7 mm x 7 mm QFH52 package It costs 6 70 in 1 000 piece quantities THAT
152. ngle bit error in a 7 bit packet but no more In case of double bit error the FEC usually adds another error when trying to correct it This is usually not an issue because the mes sage is unrecoverable but another pro tection can be added with an extra over all parity bit giving the so called SECD ED algorithm If the FEC syndrome is wrong and the parity bit is wrong there is probably a single bit error and it should be corrected However if the syndrome is wrong but the parity is cor rect or the opposite there is probably a multiple bit error and you d better throw away the packet Do you want a simulation of the Hamming 7 4 effect on the bit error rate of a transmission I did it for you with SciLab The source code is posted on the Circuit Cellar FTP site The result is given in Figure 7 First let s be honest The FEC code adds 3 bits to each 4 data bits so the number of transmitted bits is increased by a ratio of 7 4 1 75 You could spend more time to send our data but usually this is not acceptable So you need to increase the bit rate For example for a wireless system you need to increase the channel width by the same amount and this will inevitably increase the noise power by a factor 1 75 So before taking into account the positive effects of the FEC code on the bit error rate you must shift the curve by 1 75 on the right which is equiva lent to 10log10 1 75 2 4 dB www circuitcellar com CIRC
153. nline at www melabs com USB Programmer 89 95 for PIC MCUs 3s shown RoHS ES al fmm e Compliant Programs PIC MCUs including low vollage 3 3V devices Includes Software for Windows 98 Me 2K amp XP With Accessories for 119 95 Includes Programmer Software USA Cable and Programming Adapter for amp to 40 pin DIF Serial LCDs VEN melabs lt com i 2 line x 16 39 95 4 line x 20 49 95 Quantity Discounts Available Solve complex signal acquisition problems positioning amp control e environmental gt acceleration transients pressure vibration sonar eo Li 3H S Chi vIHIp ive ry T2 Disk di nC l Ready fo r De From 16MB to 128MB Available Call 530 297 6073 Sales jkmicro com www jkmicro com JK microsystems Inc International Orders Welcome micro CSUngineering e abs Qac Development Tools for PIC Microcontrollers LAD A Experimenter Boards mE Pre Assembled Boards mE Available for 8 14 18 28 SEEN and 40 pin PIC MCUs 2 line 20 char LCD Module 9 pin Serial Port Sample Programs Full Schematic Diagram Pricing from 79 95 to 349 95 BE Double Sided with Plate Thru Holes d Circuitry for Power Supply and Clock Large Prototype Area Boards Available for Most PIC MCUs 8 Documentation and Schematic Pricing from 8 95 to 19 95 CIRCUIT CELLAR Designer s Notification Network Circuit Cellar design contest entrants
154. no exponent underflow begin sout Sl 52 v Xf OULDUL Sign if mult out 17 7 71 begin MSB of product 1 normalized result gt 0 5 eout sum el e2 9 h80 mout mult outLl 9 3 end else MSB of product 0 result 0 5 so shift left begin eout sum el e2 9 h81 mout mult out 16 8 end end nonzero mult logic end always Q endmodule www circuitcellarcom gt CIRCUIT CELLAR examples of decimal values and their floating format equivalents are shown in Figure 1 Of the five operations that need to be implemented negation is very easy You just complement the sign bit The other operations are more involved and are best understood as outlines The first is multiplication MULTIPLICATION If either input number has a mantissa high order bit of zero then that input is zero and the product is zero This fol lows from the disallowing denorms If the sums of the input exponents are less than 128 then the exponent will underflow and the product is zero This follows because the sum of exponents includes the 128 offset twice and there fore 128 must be subtracted from the input exponent sum If both inputs are nonzero and the exponents don t underflow then the product of the mantissas will be in the range from just less than one down to 0 25 If the simple product mantissal x mantissa2 has the high order bit set result gt 0 5 then the top 9 bits of the product are the output mantissa and t
155. now there are four of them Although it s hard to believe from looking at the two opera tions they really are the inverse of each other I won t try to prove it here but if you write out the equations and keep track of the individual bits it works out I know because I went through the equations to prove it to myself The final basic operation is the addi tion of the round key to the data This February 2010 Issue 235 Q Listing 5 The MixColumn operation combines different versions of all 4 bytes into each resultant byte The inverse operation really does reverse the process RKRKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKE aes mixcolumn a RKRKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKE function 31 0 mixcol input 310 Tnp begin mixcol inp 7 0 inp 7 0 imul 0263npL7 0 mul DoatinpLli5 gl end endfunction mul 03Cinp 7 0 inplls 8 inp 15 8 mul D2c0mpLI5 8 mur osctmnpL23 16 inp 23 16 inp 23 16 mul_02 inp 23 16 mul O3 10npL31 24 mul 02 inp 31 24 ys inpl31 24 inp 31 224153 KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK KK aes inverse mixcolumn Su KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK function 31 0 input 31 0 beg
156. ns against a ground plane under the resistors because stray capacitance can seriously affect the filter characteristics I operated the MAX274 from a single D 11 36 83 83 OCT 2085 NR A 121 8 kt 7 10 33 d ft he j LLL tt ILU E dL Ld MANAMA UAA A d d MINAS AAU START LU kHz HES BU 3 8 kkr VEN 3 kiz STOP ame khe SUP 197 mee START LU kHz HES BU 2 8 ke 5 V supply with a simulated ground at V 2 2 5 V which requires care ful attention to keep the peak signal amplitude under about 2 V Resistors R3 and R4 in Figure 1 attenuate the 5 V square wave input by 20 dB to 500 mV with C6 centering the aver age value at V 2 Resistors R7 and R8 at the output of the filter provide another 20 dB of attenuation in preparation for the out put modulator s gain There s no capacitor in that attenuator because the modulator s input is AC coupled The MAX274 design software can tweak the resistors required for each stage to match standard 196 or 0 196 values Lacking a complete E96 or E192 stockpile I soldered pairs of resistors in series and stacked others in parallel to get the right values For tunately that s easy to do with SMD resistors on a one off board Figure 3a shows the square wave spectrum as seen at the output of the modulator with a jumper around the fil ter The third harmonic should be 1 3 of the carrier amplitude about 9 5 dB down and the split marker shows it s actually just over 10
157. ns that level trans lation devices are not needed to inter face with the 5 V ATmega32 MCU in the project So far I ve covered the project s design and explained my rationale for selecting the particular technologies I also provided important details about how both the RFID and USB flash drive host interfaces operate Next month I ll continue by describing how every thing ties together I ll include a discus sion on navigating the subtleties of the VDrive2 command set and I ll post a schematic diagram of the project lil Brian Millier brian millier dal ca is an instrumentation engineer in the Department of Chemistry at Dalhousie University in Halifax Canada He also runs Computer Inter face Consultants Pros ECT FILES To download code go to ftp ftp circuitcellar com pub Circuit_Cellar 2010 235 S OURCES ATmega32 Microcontroller Atmel Corp www atmel com VDRIVE2 Interface module Future Technology Devices International www ftdichip com DS1307 Real time clock Maxim Integrated Products Inc www maxim ic com Bascom AVR Basic compiler MCS Electronics www mcselec com MC14052 Multiplexer chip ON Semiconductor www onsemi com EM RFID Card reader Shanghai Huayuan Electronic Co Futurlec distributor www futurlec com www circuitcellar com CIRCUIT CELLAR ar s pmte What Your electrons Store Used To Be Receive a FREE Gift with orders over 5100 00
158. o Cortex M3 the news was met with some ambivalence by their exist ing MCU partners Outfits like NXP Semiconductors and Atmel had already invested heavily in ARM7 based flash MCU lineups which were selling just fine With all the major players waiting for the other guy to blink first Luminary stepped into the breach to break the deadlock They were able to successful ly establish a catalog of M3 parts and Photo 1 The new Tempest Class MCUs are the first 5tellaris MCUs to offer a high speed plenty of marketing nome and external bus interface To show off the new feature they offer an evaluation kit add on that credibility to go with Facing an upstart tightly couples the MCU with a video capture processing subsystem comprising an FPGA and M3 contender gaining traction the CCD camera e 16 Digital WO Lines e 2 Ports of USB 2 0 e SP Bus e AC97 Amplified Audio e Battery Backed Clock e 2 Serial Ports e Low Power Consumption e RoHS Compliant Our newest ARMS Linux controller the OmniEP doesn t cost an arm and a leg It delivers removable storage amplified audio ethernet and serial RS232 communication ports in a rugged and attractive enclosure Models without enclosure and LCD available The OmniEP comes preloaded with Linux to jumpstart your devel opment process with LCD and pushbutton drivers supplied Large capacity USB drives can be easily mounted in the USB port Call 530 297 6073 Email sales jk
159. o link the dispensing controller to a computer in the accounting office via an Ether net connection But running a dedicated 10BaseT connection and operating the controller as an Internet node would cost he recent commercialization of electronic devices like radio frequency identification RFID tags and USB flash drives has made it possible to design such things as vending kiosks and building access controls which are both affordable and user friendly Furthermore the availability of inexpensive modules which encapsulate the often complex protocols used by such devices is a boon to designers who don t have the expertise to augment their product s firmware I built a controller that monitors the liquid nitrogen dis pensed from a tank and bills customers for what they use see Photo 1 The tank is located in the basement of my building at Dalhousie University in Halifax Canada RFID tags costing less than 1 are issued to each customer The controller has a low cost RFID reader module After passing the tag near the controller the customer interacts with an LCD and keypad to enter the amount of liquid needed The con troller maintains a real time clock RTC cir cuit and it stores the account number sales data and a time date stamp for each transac tion All transaction records are maintained internally using E PROM A USB host port on the controller is the Photo la This is the dispenser The VDrive2 module
160. onnectivity anywhere on a motherboard The family includes the pin compatible and interchangeable wired RCM5700 Wi Fi RCM5600W wired RCM5760 and Wi Fi RCM5650W Rabbit MiniCore products feature 10 100 Base T Ethernet and secure 802 11 b g with WPA2 and 802 11i compliance for the highest levels of security It also features up to 640 KB 5RAM data storage 1 MB flash memory for program storage and two MB serial flash for mass storage Depending on the version modules include up to 52 GPIO six serial ports a serial to Ethernet bridge an embed ded Web server for greater application control monitor ing and wireless remote firmware update function ality The Ethernet RCM5700 kit costs 99 The Wi Fi RCM5600W kit with one year of free tech sup port is available now for a promotional price of 149 Rabbit Inc WWW rabbit com NM Y as IN Dpan i NJ LN I Eum Ultra Small Panel PC Got Serial CJ a Network Fanless ARM9 200MHz CPU 3 Serial Ports amp SPI Open Frame Design e 2 USB 2 0 Host Ports 10 100 BaseT Ethernel Audio Beeper Micro D Flash Card Interface Battery Backed Real Time Clock 64 MB Flash amp 64 MB RAM Linux with Eclipse IDE or WinCE 6 0 JTAG for Debuging with Real Time Trace 2 8 KERNE WQVGA 480 x 272 Resolution TET LCD with Touch Screen Four 12 Bit A Ds Two 16 Bit amp Oe 32 Bit Timer Counters The PPC E4 an ultra co
161. ooks CDs DVDs Kits amp Modules and much more www elektor com shop SJektor Elektor US 4 Park Street Vernon CT 06066 USA Phone 860 875 2199 Fax 860 871 0411 E mail sales elektor com OBD2 Analyser NG The compact OBD2 Analyzer in the June 2007 issue was an enormous success not surpris ing foran affordable handheld onboard diag nostics device with automatic protocol recognition and error codes explained in plainlanguage Now enhanced with a graph ical display Cortex M3 processor and an Open Source user interface the next genera tion of Elektor s standalone analyser sets new standards fora DIY OBD2 project The OBD2 Analyser NG is self contained and can plug into any OBD diagnostic port Kit of parts including DXM Module PCB SMD prefitted case mounting materials and cable Art 090451 71 135 50 Software Defined Radio SD radio receivers use a bare minimum of hardware relying instead on their software capabilities The Elektor SDR project by Burk hard Kainka demonstrates what s achieva ble in this case a multi purpose receiver covering all bands from 150 kHz to 30 MHz It s been optimised for receiving DRM and AM broadcasts but is also suitable for listen ingintothe world of amateurtransmissions Thedesigner s aimforthis project was to cre ate a receiver displaying high linearity and phase accuracy Development was focussed onthe characteristics that were most impor tant fo
162. ore com AVR PSoC Pro CPUI2 ARM e MSP430 Propeller a NEW V8 IDE Dinkumware libraries Power and Simplicity L Full epe 45 5 day demos on our website Hu E E E P E UT ELI T KE TEREX Turn your PC into a SPI I2C SMBus or GPIO Controller Affordable Test and Measurement Tools Bus Monitors Protocol Analyzers Host Adapters Multiplexers Battery Applications Software Micro Computer Control I C d p trethernark af Philips Corponition Www mcc us com starting t ACguisitionm ana Control 99 itii i E VEN boari C C programmable 16 10V analog inputs 8 5V analog outputs 15 TTL 7 Solenoid drivers Temperature Sensor CompactFlash Ethernet USB LCD RS 232 RS485 wireless 10 years life time Power on run within 1 second 100 Low Cost Controllers with ADC DAC UARTs 300 I Os solenoid relays CompactFlash LCD Ethernet USB motion control Custom board design Save time and money TERN 1950 5th Street Davis CA 95616 USA INC Tel 530 758 0180 Fax 530 758 0181 www tern com e sales tern com www circuitcellar com CIRCUIT CELLAR Add a color touch interface Z your ausso Pm High level R5232 Low cost interface In stock Easy to program Add color graphics to any 8 16 bit embedded system Easy fast and flexible Up and running in hours Ia Z XGC I4 TECHNOLOGY INC www reachtech com 510 770 1417
163. ork and C programming language from data types and program flow to more advanced concepts including object oriented programming 240 pages ISBN 978 0 905705 81 1 47 60 C PROGRAMMING Learn by doing C Programming for Embedded Microcontrollers If you would like to learn the C Programming language to program microcontrollers then this book is for you No programming expe rience is necessary You ll start learning to program from the very first chapter with simple programs and slowly build from there Initially you program on the PC only so no need for dedicated hardware This book uses only free or open source software and sample programs and exercises can be downloaded from the Internet 324 pages ISBN 978 0 905705 80 4 52 50 More than 100 Elektor articles included DVD LED Toolbox This DVD ROM contains carefully sorted comprehensive technical documentation about and around LEDs For standard models andfora selection of LED modules this Tool box gathers together data sheets from all the manufacturers application notes design guides white papers and so on It offers sev eral hundred drivers for powering and con trolling LEDs in different configurations along with ready to use modules power supply units DMX controllers dimmers etc In addition to optical systems light de tectors hardware etc this DVD also ad dressesthe main shortcoming of power LEDs heating ISBN 978 90 5381 245 7 46
164. ote that this can also be done using an iron on one side at a time This time let the PCB cool completely before peeling off the TRF film gently back upon itself The TRF comes in a number of colors and this process can be www circuitcellar com CIRCUIT CELLAR used to apply a silkscreen to the PCB after etching or to decorate a front panel with nomenclature Etching off the exposed copper from the PCB s laminate surfaces is not an environment friendly process I pur chased a bag of ferric chloride powder from a nearby RadioShack some time ago Most component suppliers now offer this only in liquid form This acid is the same chemical PCB houses use to etch their boards It s considered a haz ardous material both before and after use Please be careful if you use this When FeCl3 has been reduced to FeCl2 it refuses to eat up any more copper so keep track of the surface area that you etch and dispose of properly If neces sary this can be neutralized with lime or soda ash Call your local town hall for information on the proper disposal of any hazardous material The ferric chloride liquid is used directly on a PCB to etch off the exposed copper PCB manufacturers heat the acid in tanks and dip the PCB into the acid to etch the copper surface Agitation of some kind is used to keep fresh acid in contact with the copper surfaces To do this at home I used a Tupperware bowl with just a few ounces of acid in the bot tom
165. per pads with flux and sol der With a magnifier and my thinnest solder tip I ensured that none of the pads had solder bridges and that the sol der levels on each pads were appropriate After the SMT light sensors were care fully aligned atop the now coated SMT pads it was back into the oven for a reflow If you watch carefully through the oven s glass door you can actually see the point at which the solder melts and the sensors free float into their final positions due to surface tensions Once the PCB had cooled it was on to the hand soldering operation First I added wires to the unsupported vias the holes that would not contain a com ponent lead but must have a solder con nection between the top and bottom sides of the PCB Wire wrap wire was just right for this job I stripped off the insulation and stuck the bare end through the bottom side of the via and out the top I bent the wire over on the top side soldered it along the trace and clipped off the excess I then repeated the bend and solder process with the opposite end of the wire on other side All unsupported vias should be done before adding through hole components because the components sometimes cover up vias making them much hard er to solder once obstructed When through hole components are added February 2010 Issue 235 February 2010 Issue 235 Photo 4 After gently rubbing ferric chloride over the copper laminate with a small
166. pheral chips see Figure 1 I wrote the code in BASCOM BASIC AFFORDABLE LAB SOLUTION In the past I d considered Smart Cards for this application B Millier BasicCards 101 Circuit Cellar 164 But when I came to this project I con cluded that an ideal solution would include RFID tags for user validation and a USB flash drive 64 MB suffices for file transfers Cost is probably the biggest project limitation in the Department of Chem istry where I work Therefore the first thing I looked into was the cost of the RFID devices and an associated reader The cost of readers varies widely and it becomes significant if you are just set ting up a small system Fortunately I www circuitcellarcom gt CIRCUIT CELLAR found a low cost reader that would work with inexpensive RFID tags so I had a good start to my design I then investi gated the best way to incorporate a USB flash drive into my design I settled on a product from FTDI which produces var ious USB modules some of which I had used in earlier projects I consider the Vinculum VDrive2 module to be a USB flash drive coprocessor It interfaces to a microcontroller via a serial port and handles all the complexity of the drive s FAT32 file system Thirty years ago when I was building my own PC from boards and components I wrote my own simple floppy disk operating sys tem in assembly code Today however I d rather leave that chore to the pro grammers at FTDI
167. que 10 character hex code The HF tags can be used when you need the ability to store a larger amount of data in the tag With HF tags the reader is often also able to write data to the tag as part of the trans action that occurs when the tag is near it All that I needed for this project was a tag with a unique ID code nothing more Furthermore because the tag wasn t going to be embedded inside a product or worn it would be easy for the user to bring it up close to the read er removing the need for a long range system While searching the Internet I found a reasonably priced tag reader LF sys tem distributed by Futurlec The com pany s EM LF RFID reader module costs only 33 and it also carries a variety of tags plastic credit cards key fobs dog collar tags laundry tags and so on For my purposes 30 cm plastic key chain tags seemed the best choice They were only 0 80 each even in multi unit quantities I chose the EM card reader because it s easy to use and interface Physical ly it s built to be mounted like a con ventional wall lighting switch i e it can be mounted to the standard elec trical box used for lighting switches CIRCUIT CELLAR www circuitcellar com CTIA shows present le Yin and Yang of WIRELESS Any sufficiently advanced technology is indistinguishable from magic Sir Arthur C Clarke CTIA The Wireless Association has a proud and long standing tradition of bringi
168. r uCAM 232 uCAM TTL a L 3 EMC RF amp EMC Spectrum CANminiBOX RF Generator emPC x133 High res extremely low noise portable 6GHz RF generator Embedded controller series 2 x CANbus Ehternet USB2 0 CF Electronic DC Load 60 100 120MHz USB 14 bit ARB with USB RS 232 LAN GPIB Const current resistance conductance voltage amp power modes Fantastic array of stock and custom switching devices Network serial product easily without a PC using this 28 cable 89 Analog input bluetooth wireless modules 433 868 915MHz Ready to go out of the box FPGA DSP designs for beginners and experts KK Systems Add 1 16 COMports via your PC s USB Port easily 9p 9p or 25p 25p self pwrd isolated RS232 RS422 485 180 PL1012 PL1216 PSA2701T APSIN6000 DG3061A 3101A 3121A USB COM really like this scope adapter its meant for teaching electronic experiments but it s ideal for engineers too Alan Lowne Saelig CEO Call 1 888 772 3544 to get a free Starbucks Card with your gt 50 order While supplies last not available with any other offers Worlds s Fastest Bea 2 ch 12GHz sampling scope for high speed electrical signals RF Testing EMI Tents Portable RF test enclosures amp shielding tents with external frame TorqSense ie es ias tis Configurable patented USB output non contact SAW digital rotary torque transducers with
169. r a top notch DRM receiver and the end result is a receiver with remarkable inter ference rejection characteristics Ready populated and tested board Art 070039 91 139 60 February 2010 Issue 235 I planned to use an Arduino Duemilanove board to generate the time code so my first thought was to divide its 16 MHz clock to 60 kHz using the chip s internal hardware Alas 60 kHz is not an integral frac tion of 16 MHz the exact ratio is 266 2 3 Dividing 16 MHz by 267 the closest integer introduces a 0 125 fre quency error that under ordinary circumstances probably wouldn t mat ter After all 59 925 kHz is pretty close to 60 kHz right However the C Max WWNVB receiver I planned to use in the SJ1 60kHz Attenuated i At ground plane exit 60kHz Filtered R7 9 1k GOkHz Carrier H8 MAX274ACN 1k 60 kHz 8 pole LPF Butterworth 0 dB gain 60 kHz Figure 2 The MAX274 implements an 8 order Butterworth low pass filter that converts a square wave into a nearly perfect sine wave The output attenuator reduces the amplitude in preparation for the modulator s gain clock has a a resonant bar antenna bandwidth which implies a band don t give its overall bandwidth but and series crystal filter to extract the width of about 0 6 Hz A much the chip documentation lists a nomi 60 kHz carrier A single crystal filter broader crystal filter with Q 10 nal 10 Hz bandwidth Because the might
170. r com esum P i E s wu mm immi a LLI oH z E nus manans Photo 1 This board simulates the NIST WWVB time signal transmitter The analog circuitry generates and AM mod ulates a 60 kHz sine wave while the Arduino board plugged underneath provides data bits at the proper times The circuitry surrounding the MAX274 filter in the right front corner is sensitive to stray capacitance no ground plane allowed ordinary audio techniques Unlike the computer generated voice announcements on the more familiar WWV and WWVH stations the time information is also peculiar WWYVB sends pure machine readable data in BCD format at one bit per second Yes that s 1 baud Steven Nickels described his WWVB based Time Server in Circuit Gellar 220 and gave an excellent description of the WWVB time code format so I won t cover that same material Keep in mind that he lives 50 miles from the 50 kW WWVB trans mitter and I live half a continent away in the Hudson Valley so we have entirely different attitudes toward RF reception and data reliability For our purposes here it s enough to know that the time code frame repeats each minute with pulse width modulated PWM frame mark ers and data bits The RF signal uses amplitude modulation the carrier power drops 10 dB at the start of each second at the On Time Mark and returns to full power at the end of the PWM pulse The pulses have three durations 800 ms frame ma
171. rcom CIRCUIT CELLAR Convolutive coder H Figure 9 This diagram shows the main building blocks of a convolutional coder and decoder The idea is to send the input datastream and also a derived stream that take into account the data s history Output bit stream ILI UL Maximum likehood decoder Viterbi algorithm Transmission Interleaver EUM Robert Lacoste lives near Faris France He has 2O years of expe rience working on embedded systems analog designs and wire less telecommunications He has won prizes in more than 15 international design contests In 2005 Robert started a consult ing company ALCIOM to share his passion for innovative mixed signal designs You can reach him at rlacoste alciom com Don t forget to write Darker Side in the subject line to bypass his spam filters p ROJECT FILES To download the code go to ftp ftp circuitcellar com pub Circuit Cellar 2010 235 D es C Berrou A Glaviuex and P Thitimajshima Near Shannon Limit Error Correction Coding and Decoding Turbo Codes ENST Bretagne 1993 www elec enst bretagne fr equipe berrou Near 20Shannon 20Limit 20Error pdf A Blais SciLab Convolutive Code Library SciLab www SciLab org contrib index contrib php page displayContribution amp fileID 257 C Langton Coding and Decoding with Convolution al Codes 1999 http complextoreal com chapters convo pdf C E Shannon Communicat
172. re provides a traditional scope interface along with auto measurements the ability to store and export waveforms a function generator a logic analyzer a spectrum analyzer a vectorscope and more To order the PropScope USB Oscilloscope 32220 249 99 visit www parallax com Or call our Sales Department toll free 888 5 12 1024 Monday Friday 7 a m 5 p m PST Prices subject to change without notice PropScope Propeller Parallax and the Parallax logo are trademarks of Parallax Inc PropScope NA ANS Friendly microcontrollers legendary resources www parallax com Z 3 CIRCUIT CELLAR THE MAGAZINE FOR COMPUTER APPLICATIONS c DICLL by Michael Chan Using U5B for Computer Interfacing Projects Are you ready to use the power of USB technology for computer control You can convert a Microchip Technology PIC18F4550 and a few other parts into a plug and play control device in parallel or serial mode This project will simplify your next computer control application It s time to revive your favorite printer port control projects Photo 1 This is a prototype converter built for computer omputer interfacing used to be pretty straightfor control projects ward when using the parallel serial port I wrote several articles about projects such as LCDs home automation and robotics control that used the computer printer port In fact the majority of PC inter
173. really a full fledged system on a chip because it con tains an MCU core 64 KB of flash mem ory 4 KB of SRAM dual DMA con trollers a UART a SPI and a PS2 port and a lot of general purpose I O The chip is delivered unprogrammed but FTDI offers several versions of firmware which you can download to the device s flash memory via its UART port and the bootloader firmware built into the device FTDI provides a PC application called VPROG that enables you to pro gram and reprogram the firmware into the VNCIL chip using either a USB port or a legacy COM port a version of the program exists for each As I write this article the following versions of the firmware are available disk drives and peripherals VDAP disk and FTDI interface VDIF disk and MP3 player function VMSC disk PC monitor and slave port VDPS and communication class device VCDC Purchasing an FTDI VDRIVE2 OEM module makes sense for a one off project like mine For about 13 more than the cost of the VNCIL chip alone you get a small module containing the VNCIL chip a USB socket a traffic LED and a cable to connect to its eight pin SIP header This module comes preloaded with the VDAP firmware so you don t have to do it yourself using the bootloader Although the VNCIL chip operates on 3 3 V you must supply the VDRIVE2 module with 5 V which is needed to supply the USB port power The VDRIVE2 I O ports are 5 V logic tolerant which mea
174. rkers 500 ms bina ry 1 bits and 200 ms binary 0 bits The low carrier frequency and slow pulse timing requirements certainly www circuitcellar com CIRCUIT CELLAR simplified this part of the project CARRIER GENERATION Operating an actual radio transmit ter requires conformance with a wide a nre Waters Glogs FC Tbe men EUN e ow variety of rules and regulations not to mention possessing a license authoriz ing the broadcasts The technical speci fications may well present the smallest part of the overall challenge My transmitter required just enough power to get from one end of my electronics workbench to the other akin to the old amateur radio technique of trans mitting into a dummy load to test an adjacent receiver using the signal leaking through the coaxial cable shield Indeed the WWVB carrier has a 5 km wavelength that makes any desktop scale antenna essentially equivalent to a dummy load Fok ap line T uam me ST Tekun l n A1 e m TEES FAP leapt g February 2010 Issue 235 UJ BOARDS BOOKS DVDs AND MORE AT WWW ELEKTOR COM SHOP Elektor Shop The world of electronics at your fingertips DOOK APLETE PRACTICAL CON SUREMENT SYSTEMS USING A PC Circuit design and programmin gin CH and Visual Basic Circuit design and programming in C and Visual Basic Complete practical measurement systems using a PC This is a highly pra
175. s uses a ring of numbers that are projected onto the dial s face see Photo 1 This month I ll present a project that enables you to use the sun to tell time While I could tune into NIST radio station WWV or connect to the Internet accurate to standards that far exceed my needs I choose to use the sun After all it s Photo 1 This sundial uses a shadow mask to display the actual hour glyph on the central area located beneath the ring As the sun moves the hour s glyphs move across the face of the dial CIRCUIT CELLAR www circuitcellar com not where you re going in life but how Luminance Example intensity By measuring the output lev you get there That s what makes life 1 lux Full moon overhead els from each sensor you can deter interesting 100 lux Very dark overcast day mine if a sensor becomes shaded when The project consists of a directional 400 lux Sunrise or sunset the sensor or source moves off axis light sensor that uses a shadow cast by 1 000 lux Overcast day The shaded sensor or sensors helps the sun to determine its relative position 10 000 lux Full daylight determine the direction in which the A microcontroller monitors the sensor s output and determines which way the sensor must be moved to remain facing the sun By tracking the sun s movements over time it calculates the time of day and sets its RTC The time is displayed on a multipl
176. sponge the unmasked copper areas are eventually dis solved by the acid wash You can see traces on the reverse side of this etched PCB show ing through the fiberglass board remember to solder each lead to both sides of the PCB Soldering both sides not only completes electrical connec tions but also adds to the component s stability The connector can be soldered to only one side of the PCB It should be treated as such in the layout process by making all connections to it on the side of the PCB to which it will be soldered If you forget to do this treat it like an unsupported via that is use a small piece of wire wrap wire through the connector s hole and soldered along the trace on the side opposite that of where the connector will be soldered Leave the wire sticking through the hole and insert the connector so that the wire and connector pin go through the hole together After all of connector pins are soldered you can clean off the flux residue on the board You might need to use a solvent unless you ve been using water soluble flux SENSOR MODULE MOVEMENT With each of the four sensors config ured to give approximately 2 V in nor mal sunlight you need a way to produce a shadow that falls in the center of all sensors when the sun is at 90 to both perpendicular planes of the sensor sur faces A small baffle centered between the sensors will cast a shadow on one or more sensors as the module is moved off
177. t sbox x reg 31 24 sbox x reg 23 16 sboxix reg 15 8 sbox x regl7 0 AOP_ISBOX x_reg_nxt ibox x_reg 31 24 ibox x_reg 23 16 ibox x reg 15 8 ibox x reg 7 0 AOP SHROW x reg nx iw peg 31 24 1 z reg 25 16 y reg L15 8 x_reg 7 0 AOP ISHROW x reg nx iy preg 31 24 z_reg 23 16 w reg 15 8 x_reg 7 0 AOP MXCOL mixcol x reg invmixcol x reg x reg key reg 63 32 x reg AOP IMXCOL x reg nx AOP ADDKEY x reg nx default X reg nxt endcase end L t X reg nxt L t KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK y register next input x KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKE always aluop_reg or w_reg or x_reg or y_reg or z_reg or key_reg begin casex aluop_reg AOP_SBOX y_reg_nxt sbox y reg 31 24 sbox y reg 23 16 sboxty reg 15 8 1 sbox y_regl7 0 AOP ISBOX y reg nxt ibox y_reg 31 24 ibox y_reg 23 16 iboxty regLl15 8 aboxiy reg 7 0 3s AOP SHROW y reg nx ix peg 31 24 1 w regL25 15 4 z_reg 15 8 y_reg 7 0 AOP ISHROW y reg nx z_reg 31 24 w reg 23 16 Xx reg 15 8 y_reg 7 0 AOP MXCOL mixcol y reg invmixcol y reg y reg key reg 95 64 y_reg AOP_IMXCOL y reg nx AOP ADDKEY y reg nx default y reg nxt endcase end t t y_reg_nxt t t xxkkkkkkxkkkkkkkxkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk
178. t is cen tered on the mask on the inside I ve used a clothes iron to reheat the TTS and transfer the toner mask to the PCB laminate This time I tried a plastic laminator Using the laminator lets the process occur under more controlled conditions I did find that I really had to let the laminator get hot before the toner would transfer properly The Ready light might indicate a tempera ture that s fine for laminating ID cards but I found it needed a good 15 minutes until it was hot enough to remelt the mask Also after putting the TTS pouch through the laminator a couple of times I found placing it in water right away quickly reducing the temperature helped the toner to lock onto the cop per After only a few seconds of soaking in water the TTS carrier floated free of the PCB laminate The toner was now sticking to the copper In the past the PCB was ready to be etched in acid but now there is an addi tional step It seems that the toner can actually be quite porous and invite the acid to etch areas within the mask cre ating pinholes or even hairline cracking The new step seals the toner surface with a new material that prevents this from happening The toner reactive foil TRF completely encapsulates the toner by bonding to its surface without bond ing to the copper laminate A piece of TRF is wrapped around the PCB lami nate covering the toner masks on both sides Once again it is passed through the laminator N
179. t out the problems of over exuberant product design but my job at Circuit Cellar is to entertain all technological ideas even the crazy ones have the luxury of thinking what if with out the constraints of time budget or rationale and don t have to make a real product at the end of the process Some might call that a virtual design world with no responsibilities Around here we simply call it a magazine steve ciarcia circuitcellar com CIRCUIT CELLAR www circuitcellar com Digis Wireless Contest 20 000 in Cash Prizes Digi International is challenging anyone with a good idea no matter how big or how small to participate in our Wireless Green Design Contest iDigi Starter Kits provide the hardware software and services to grow a good idea into a great green solution Buy a 149 kit submit your design and you could win Go green Go Digi www digi com gogreen USB Oscilloscope The PropScope 32220 249 99 is a two channel oscilloscope that is capable of reading 25 million samples per second with ten bits of resolution over one two ten or X PN twenty volt peak to peak waveforms Power is provided through the USB port requiring only a single cable to connect the PropScope to any laptop or desktop PC The included DAC card provides an analog trigger a four bit digital trigger an eight bit digital to analog converter and a four bit NTSC PAL output The included softwa
180. t scroll and crawl TTL 232 and SPI control ports Any size for custom fonts Vector and bitmap graphics www decadenet com Le DECADE ENGINEERING 503 743 3194 Turner OR USA PDQ Board A Fast I O Rich Single Board Computer 159 100s Low cost 2 5 x4 C programmable computer 16 bit HCS12 processor clocked at 40 MHz 8 PWM 8 counter timer and 8 digital I O 16 10 bit A D inputs Dual RS232 485 ports SPI and IC ports 512K on chip Flash 512K RAM with Flash backup Plug in I O expansion including Ethernet Wi Fi GPS 24 bit data acquisition UART USB Compact Flash card relays and more February 2010 Issue 235 m Q Tha original Controller Araa Network CAN to A5232 serial convertor 1 M N Ofo ya CAN232 Features Free sample programs pets a Naat CANUSB Features Small size 2 7 by 1 27 Des deir i component 100 Bandwidth up to 125Kbit PC Mi nux support Both 11 amp 29 bit ID support Both 11 amp 28 bit ID support 32 Message Receive FIFO Simple CAN logger included Works up to 1Mbit CAN Free Threaded Windows DLL Simple ASCII protocol Firmware upgradable via USB Supports RTRFrames j Sample programs in C C VB Max 230Kbaud RS232 Delphi C amp PureBasic etc Firmware upgradable JA No need for external power No drivers needed Works up to 1Mbit CAN 0S independant Supports RTR Frames USB 2 0 Full Speed 2 Free USB drivers CE Approved Order o
181. te 6 byteL6 byte 5 byte 5 byte 7 end endfunction function 7 0 mul 0d input 7 0 byte begin mul Od f byte 4 byte 5 byte 3 bytel 7 byte 2 byte 6 byte 1 byte 5 byte 0 byte 7 byteL6 byte 0 byte 5 byte 7 byte 5 byte 6 end endfunction function 7 0 mul 0e byte 71 byte 5 byte 6 byte 6 byte 4 byte 5 byte 5 byte 3 byte 7 byte 4 byte 2 byteL3 byte 1 byte 2 byte 0 byte 7 byte 1 byte 0 byte 71 byte 4 byte 6 byte 3 byte 5 byte 2 byte 7 byte 4 byte 5 byte 1 byte 6 Dyte 3 byte 21 byte l1 byte 01 7 bytel 6 byte 4 byte 5 byte 3 byte 4 byte 2 byte 3 byte 1 byte 6 byte 21 byreLli l byteL 71254 input 7 0 byte begin mul Oe byte 4 byte 5 byte 3 byte 7 byte 2 byte 6 byte 1 byte 5 byteLO byte 5 byteL6 byte 0 byte 5 byte 0 byte 5 byte 6 end endfunction www circuitcellarcom gt CIRCUIT CELLAR the opposite direction These two oper ations are the only ones that are simple enough except for the key addition to specify directly in Listing 1 without resorting to functions The third operation is called Mix Columns in the standard and it is the most difficult to comprehend It operates on individual registers in this impleme
182. teresting project The dig ital circuitry and firmware consist mostly of counters but as always the analog circuits presented some challenges Because this was an entirely indoor application I decid ed the clock should set its time auto matically using a WWVB radio receiv er That meant I had to build a very low power trans mitter sending a WWVP style time code signal allow ing me to check out vagaries of RF propagation In this column I ll describe the WWVB simulator shown in Photo 1 In my next col umn I will cover the other end of the project where RF once again becomes bits TIME CODING Radio station WWVB operated by the National Institute of Standards and Technolo gy NIST continuously transmits a time and frequency reference signal on a 60 kHz carri er Nearly all other radio services use fre quencies denominated in megahertz but WWVB lies in the Low Frequency LF band It s a radio service with circuitry that uses PWM5 T1 Input 74HC109 60kHz Square 60kHz Attenuated 74HCOO 20 dB Attenuator R4 500 mVpp output centered at 2 5V 00 4 IC3B 74HC00 60kHz Buffered the clock logic with Figure 1 The 12 MHz crystal oscillator and divider chain produce a 60 kHz square wave known test data The 20 dB attenuator reduces the amplitude to ensure that the MAX274 filter shown in and without the Fiqure 2 has enough headroom to operate properly CIRCUIT CELLAR www circuitcella
183. tively uses only 7 bits which would otherwise mean that 1 bit of every byte would be clever 100 MHz MSO 8M Samples 14 bit Two mixed signal triggers Protocol decoding Spectrum analysis Symbolic maths Custom units Copy amp paste Signal generator USB or Ethernet 4 or 8M samples storage 100 MHz sampling Dual 10 12 or 14 bit ADC Ext Trigger 8 Digital Inputs 1 MSa sec charting High Resolution Spectrum Analysis Capture a 50Mhz bandwidth with 50 Hz resolution Zoom on any point Using the 14 bit ADC you get a 85 dB noise floor over the whole bandwidth Use the hardware moving average filter to further improve this www cleverscope com www circuitcellar com CIRCUIT CELLAR msb ibox 128 h1 2b047eba d626e169146355210c d known significantly weakening the strength of the encryption The inverse of this operation is called the Inverse S Box and it s shown in Listing 3 As an example an input byte of 0x00 is mapped to 0x63 by the sbox function If you look up 0x63 in the ibox function you ll see that the result is 0x00 So it is for each The next operation is called ShiftRows in the standard which is confusing because it seems to be oper ating on columns of bytes in Figure 1 This is because the examples in the standard rotate the data in the figure by 90 counterclockwise compared to what you see here Keep this in mind if you try to compare this implementa tio
184. to 800 nA and further reduced to 400 nA if the self wake up feature is not enabled The ETRAS series is available from Lemos International Telegesis s U S distributor Pricing starts at 18 in small quantities Lemos International Corp www lemosint com NPN AE E m E ge f uL m La P fh mm B Easy Fd f a a e dded B L Lir 41 ux um J E iD d j LLO E Je g OmmniFi 1 QUICKLY AND COST EFFECTIVELY MAKE YOUR PRODUCT WIRELESS TELDE RF MODULES LOW COST LONG RANGE GPS Modules Fc ECT GPS MADE SIMPLE 3 RF MODULE eee RXM GPS SR LOT 10090 I RXM GPS SG TRANSMITTERS e RECEIVERS High Sensitivity High Performance TRANSCEIVERS Easy Serial interface Ultra Compact E Low Power Consumption Low Cost FI ge Th se easily applied GPS modules blend performance and cost effectiveness TIGE single compact SMD package The low l power chipset minimizes power consumption and conl c provides exceptional sensitivity Choose either an COMMAND CONTROL int grated or external antenna KEYLESS ENTRY INTEGRATED CIRCUITS ENCODERS DECODERS TRANSCODERS we X m a id w ANY d a oU N N NU ast ow aa NP NE We brought you the world s easiest to use DOS controllers and Development Systems THE FAST TRACK TO WIRELESS SUCCESS Link development systems contain everything borieeded to evaluate the Linx product of you choice and implement it in record time OEM PRODUCTS
185. ts plus one hardware multiplier on the Cyclone II FPGA out of 33 000 logic elements and 70 multipliers while the adder takes about 220 logic elements The timing analyzer suggests that the purely combinatorial multiplier should be able to run at 50 MHz and the adder at 30 MEZ and in fact run fine at 27 MHz DSP APP amp TESTING To test the floating point modules I wrote a DSP application to filter an CIRCUIT CELLAR www circuitcellar com gece ILbank 3 PORT INTERFACE e Ay di L isa Ei a on rs Wa 4 r ny 4 A P te gt j M Vires m a i r 3 Hp ji ii HE iG ig mE 2 K j j 1 j J f IN A gi B Pn A MF m M d Fi NE i w MOX Cf igs E Ca ia ad LA fi i al E fum amm a EI RS 485 to Ethernet Converter Powerful feature Protocol converter RS485 between Ethernet Offer TCP IP Communication to Devices with RS485 I F Conan HET eati nm Dpecirication a ee Network TCP UDP DHCP ICMP IPv4 ARP IGMP PPPoE Ethernet Auto MDI MDIX 10 100 Base TX Auto negotiation Full half Duplex Serial RS485 3 Ports 1 200 115 200 bps Terminal block I F Type Control program IP Address amp port setting serial condition configuration Data transmit Monitoring Accessory Power adapter 9V 1500mA LAN cable Etc DIP Switch 485 Baud Rate setting LED Power Network 485 Port transmission signal tC J ILbank Fimraenasa in Dime t
186. tuff While there is just one AES algorithm there are three dif ferent flavors the word used in the standard that depend on the cipher key s length For this description I ll use the most common version which is AES 128 It uses a cipher key that is 128 bits long HIGH LEVEL VIEW The AES algorithm is a type of symmetric block cipher This means the algorithm uses the same key for encrypting and decrypting the symmetric part and operates on blocks of data of a particular size transforming a fixed size block of data known as the plaintext into an identical size block of encrypted data called the ciphertext and vice versa The block size for AES is 128 bits which conveniently fits into four 32 bit registers as shown in Figure 1 The AES algorithm applies a handful of fairly simple oper ations to these data bits in a series of rounds a fancy way of saying iterations For AES 128 there are 10 of these rounds nine of which are identical The output of each R February 2010 Issue 235 round is used as the input to the next round and the output of the final round is the encrypted data Decryption reverses this process step by step to transform the encrypted data back to its original form During each round the intermediate data is combined with a round key which is an expanded version of the origi nal 128 bit cipher key I ll cover the algorithm to generate these round keys later in this article Using a
187. ughout a building and the area around it AFFORDABLE FUN I currently write VHDL code for var ious aerospace related FPGA applica tions As you can imagine the test requirements for these applications are rigorous If you will pardon the pun the exclusive use of hardware testing in lieu of simulation for aerospace circuit development and debug will not fly Therefore I was pleased to embark on a course of writing test benches and using simulations to create and debug new designs This effort has resulted in the realization that within a test bench a simulation can support a sys tem controller that generates the same bus cycles as the hardware based rs232 syscon module effectively using text input and output files to deliver commands to the system under test and record the responses from the system This approach has the advan tage that a particular set of syscon commands can be used with very lit tle modification during both the sim ulation and hardware checkout phases of design and test I have not gone to the trouble to make the output identical between the two modules but it could be done N Qo easily The input is mostly identical The only modification is the addition of a simulation delay value per com mand line for sim syscon The VHDL source code for this module and exam ple I O text files have been included with the other Verilog source files posted on the Circuit Cellar FTP site
188. unit is parameterized so that the width of the data bus determines the width of the dd field Likewise the address bus can be scaled to any width Even the quantity field can be enlarged if Initialize issues a reset pulse desired Output formatting for reads is automatic www circuitcellarcom gt CIRCUIT CELLAR date character must be an enter character so it sets its divider to the count derived from measuring the February 2010 Issue 235 N Q February 2010 Issue 235 intervals and implements the new baud rate automatically If the target system uses a programmable system clock generator the user can adjust system clock frequencies under regis ter control and the board s UART still easily adjusts to the new baud rates on the fly This is excellent for the human user who can see a prompt after simply pressing Enter a time or two Now that I think of it wouldn t it be a fun feature to add an automatic TX RX swapping function for those times when the lines end up connect ed backwards It might save some head scratching But I digress The other part of the support envi ronment is the register block For the most easygoing environment I ve chosen to embrace the use of internal tristate gates Some have preached against the use of internal tristates citing inherent difficulties in formal verification methods test coverage and lack of ability to completely avoid glitc
189. ver used simul taneously it s possible to multiplex both modules to the single serial port present on the ATmega32 microcontroller using an ON Semiconductor MC14052 multi plexer chip You might wonder why I didn t use the USB flash drive to handle the con troller s nonvolatile storage needs Why bother with the two 24AA1025 1 024 KB PC flash memory devices at all The main reason is that I wanted a user friendly design I wanted to be able to merely plug a USB flash drive into the externally mounted VDrive2 module once a month to download the transac tion figures If the USB flash drive were to be used to store all the transaction data as it was being collected the drive would have to be connected all the time That would involve mounting it inside the controller s cabinet behind a locked access door otherwise someone could just steal it While the current cost of a 64 MB February 2010 Issue 235 17 Embedded Single Board Computers High End Performance with Embedded Ruggedness TS 7800 500 MHz ARM9 Low power 4W 5V 128MB DDR RAM 512MB high speed 17MB sec onboard Flash 12K LUT customizable FPGA shown MM 3 M F i h 2M EL Internal PCI Bus PC 104 connector So CREE a T ae ag i 2 host USB 2 0 480 Mbps a 2 SD sockets 10 serial ports a 110 GPIO 5 ADC 10 bit a 2 SATA ports Sleep mode uses 200 microamps Gigabit ethernet and backward compatible with TS 72xx Boots Linux 2 6 in 67 se
190. w Cost High Quality b PCB Prototypes e Easy online Ordering e Full DRC included e Lead times from 24 hrs Optional Chemical Tin finish no extra cost SIL EC ur PCB Follow the production of your PCB in REALTIME email salesS pcb pool com Toll Free USA 1877 390 8541 www pcb pool com E February 2010 Issue 235 j e uA 3 i SN 4 3 E T JTAG Debug Por USART Serial Port SAMZU High speed USB Device Port Tu UART Serial tiae n M l amp bit Color QVGA TFT with Resistive Touchscreen 2 Gb NAND Flash lon reverse ME I amp bit pe b oci R Backup Batte o om SDCard SDL0 MMC Interface Zigbee Connector iv P c M ier opone Headphone Audio Line In ru Di Jv Beta LAYOUT like the Humvee of MCUs except it gets good mileage and does n t cost a lot Check out the latest mbed mod ule from ARM starring an LPC1768 in Photo 2 It s just 99 which is all the more a bargain since the web based tools are free Refer to my June 2 009 article Easy E mbed for more information Circuit Cellar 2 27 Atmel s first M3 offer ing the SAM3U is super sized as well with up to 256 KB flash memory and 56 KB SRAM plus even more pins up to 144 to play with notably includ ing high speed USB 2 0 480 Mbps Photo 3 is FOR COMPUTER APPLICATIONS Make sure you re signed up to receive Circuit Cellar
191. w circuitcellar com subscribe Circuit Cellar Subscriptions P O Box 5650 Hanover NH 03755 5650 Address Changes Problems E mail subscribe circuitcellar com 860 875 2199 Fax 860 871 0411 E mail info G circuitcellar com Editorial Office Editor Circuit Cellar 4 Park St Vernon CT 06066 E mail editor 9 circuitcellar com New Products New Products Circuit Cellar 4 Park St Vernon CT 06066 E mail newproducts G circuitcellar com 860 875 2199 E mail reprints circuitcellar com H Authors e mail addresses when available are included at the end of each article CIRCUIT CELLARG THE MAGAZINE FOR COMPUTER APPLICATIONS ISSN 1528 0608 is published monthly by Circuit Cellar Incorporated 4 Park Street Vernon CT 06066 Periodical rates paid at Vernon CT and additional offices One year 12 issues subscription rate USA and possessions 29 95 Canada Mexico 34 95 all other countries 49 95 Two year 24 issues sub scription rate USA and possessions 49 95 Canada Mexico 59 95 all other countries 85 All subscription orders payable in U S funds only via Visa MasterCard international postal money order or check drawn on U S bank Direct subscription orders and subscription related questions to Circuit Cellar Subscriptions P O Box 5650 Hanover NH 03755 5650 or call 800 269 6301 Postmaster Send address changes to Circuit Cellar Circulation Dept P O Box 5650 Hanover NH 03755 5650 Circuit Cellar makes no warranties
192. which the USB flash drive pluas into is tucked away on the left side panel because it is not accessed by the liquid nitrogen customers b Almost all of the cir February 2010 Issue 235 aspect of the design that makes it so user friendly It enables me EN o cuitry is mounted behind the front panel on the bottom The main power supply components are mounted in the enclosure s body The VDrive2 module is visible above the main circuit board The solenoid valve is on the right CIRCUIT CELLAR e www circuitcellar com the controller via a 4 x 20 LCD and a numeric keypad The transaction data and RFID identification code memory is provided by two Microchip Technology L273 TA 41s T el B zI Lel Lol Lc x o D 3 V Coin cell 4 x 20 LCD 74C922 LF RFID Reader RFID Tag DS1307 RTC 1 024 KB IC EEPROM x2 Serial in out m d Ww P gt VDrive 2 USB Flash drive Dev select ATmega32 E cua Solenoid valve Figure 1 The project is built around an ATmega32 You can see how the RFID reader and the VDrive2 module interact more than using a USB flash drive In this article I ll describe how I simplified the design by using an off the shelf RFID reader module and a Vinculum VDrive2 module which handles reading and writing files to a USB flash drive All told the project consists of an Atmel ATmega32 microcontroller and just five other peri
193. ww daintree com EFM32G Cortex M23 flash MCU Energy Micro www energymicro com LPC1300 and LPC1700 Cortex M3 flash MCU NXP Semiconductors www nxp com STM32W Cortex M3 flash MCU with IEEE 802 15 4 radio ST Microelectronics www st com Stellaris 9000 series Cortex M3 flash MCU Texas Instruments www ti com stellaris prhome TMPM 360 and TMPM 370 Cortex M3 flash MCU Toshiba America Electronic Components February 2010 Issue 235 37 February 2010 Issue 235 UJ Qo ABOVE THE GROUND PLANE by Ed Nisley Totally Featureless Clock rat 1 WWVD Simulator Ed began constructing a Totally Featureless Clock for a friend by first building a WWVB simulator That s mostly a simple matter of software But there s also the analog chain a crystal oscillator a steep filter built around a MAK2 74 and a feeble power amp driving a bar antenna friend recently asked me to build a wall clock for her kitchen Although you can buy a clock at any big box retailer her single highest priority requirement elimi nated an off the shelf solution the clock should never ever display an incorrect time She had several other challenging design specs no blinking or flashing no seconds or date display no alarm or snooze function and huge blue LED digits Basically she wanted a clock with an utterly simple user interface just the time all the time Constructing her Totally Featureless Clock turned out to be an in
194. y Trade Show Executive CTIA The Wireless Association 23 ri 929 9 3 gas as e e of 2008 This is only the beginning Please go to www ctiashow com for registration information uA 12 eight conductor cable exits from the back of the unit All you need to do is supply the unit with 9 to 12 VDC and monitor the 9 600 bps RS 232 level signal on the TxD wire The reader s front panel contains a two color LED that illuminates red when the unit is powered up and flashes green when a valid RFID tag is nearby The unit also has a loud piezo buzzer that beeps when a matching RFID tag is sensed These built in user feedback features are handy because you don t have to write Ato Cire DISCOVER 5 E a WAI d j Emerging 1 BOO UE Solutions DS DESIGN PRINTED UE code or use any I O port lines for them There are also control wires to external ly control the buzzer and the LED but I didn t use them Whenever a valid RFID tag is near the reader sends a message via its TxD wire in the following format STX ID1 ID2 ID3 ID4 ID5 ID6 ID7 ID8 ID9 ID10 ETX Note that STX is ASCII code 02 ETX is ASCII code 03 IDx is 10 ASCII Equipment Demonstrations Solutions THERE S NO OTHER SHOW LIKE IT IN CONFERENCE amp EXHIBITION April 6 8 2010 MEETINGS amp EDUCATION April 6 9 2010 Mandalay Bay Resort amp Convention Center Las Vegas Nevada
195. y2 n 2 To download the file Fourth order IIR filter pdf go to ftp ftp circuitcellar com pub Circuit Cellar 2010 235 Six update the filter state for the next time step Seven multiply y2 n by the D EFERENCES gain input to form the filter output Eight convert the filter output back to 1 R Munato Survey of Floating Point Formats www mrob com pub 16 bit fixed point for the audio output math floatformats html codec 2 F Fang et al Floating Point Bit Width Optimization for Low Power In the code file Fourth order IIR fil Signal Processing Applications Carnegie Mellon University 2002 ter pdf posted on the Circuit Cellar FTP site the floating point multiply 3 Lightweight Floating Point Arithmetic Case Study of Inverse and accumulate MAC operation Discrete Cosine Transform EURASIP J Sig Proc Special Issue on sequentially takes its inputs from two Applied Implementation of DSP and Communication Systems 2002 registers f_coeff and f value and places the result in f mac new Most 4 J Ying Fai Tong et al Reducing Power by Optimizing the Necessary of the state machine consists of five Precision Range of Floating Point Arithmetic IEEE Transactions on Very MAC operations for each of the two Large Scale Integration VLSI Systems Volume 8 Issue 3 2000 SOSs State 15 stops the execution of the filter until the next audio sample becomes available States 1 to 5 com put
196. you see all the parts 5 VDD VOUT GND NC GND NC NC REXT 4 NC REXT R1 100k 9 VDD VOUT E NN GND 5 NC NC REXT VDD VOUT GND NC Figure 1 A PCB begins with the schematic of all the parts that will be mounted on the board Here four Intersil I5L29102 light sensors and associated components are combined to create a sensor module February 2010 Issue 235 e February 2010 Issue 235 from your schematic drawing with their pins pads interconnected The connec tions are elastic that is they stretch as you move the part It s a good idea to resize the standard PCB outline before you start positioning parts Add any notches holes or radii you may require to the PCB This simple circuit has four sets of components I required the sensor in each set to be located as close as possible to a central point So these were placed at 90 with respect to one another top left bot tom and right Because the sensors are SMT parts and all connections to the sen sor are on the same side of the PCB using through hole parts for the resistors and capacitors means having to add fewer unsupported vias One of the things you can t do on a homemade PCB without nasty chemicals and high currents is grow plated through holes So every time a trace on one side of the PCB needs to connect to one on the other side through a drilled via you must solder a wire to both sides The best way to do this is to place a
197. yte Dim BufferSize As Long ReDim Buffer 8 Dim rd As Byte BufferSize 3 Buffer 0 0 Buffer 1 pn Buffer 2 da If pn 1 Then HIDComml Writelo Buffer End If If pn 2 Then HIDComml Writelo Buffer BufferSize Buffer HIDComml ReadFrom BufferSize End If If pn 3 Then HIDComml Writelo Buffer End IT End Sub da As Byte BufferSize BufferSize b Rem Printer Port Control Chan Private Sub Commandl Clickt Dim pd cd As Byte Dim pn As Integer Parallel Show pd CByte Textl Text cd CByte Text2 Text pn pd If pn lt 1 Or pn gt 3 Then pn 1 Call CallPort pn cd End Sub Private Sub CallPort pn As Integer da As Byte If pn 1 Then VbOut 888 da End If If pn 2 Then da VbInp 889 End If If pn 3 Then VbOut 890 da End If End Sub CIRCUIT CELLAR e www circuitcellar com ANO RAO ANT RA1 VREF CVREF AN2 RA2 VREF AN3 RA3 TOCKI C1 OUT RCV RA4 SS HLVDIN C20UT AN4 RA5 OSC2 CLKO RA6 OSCI CLKI RA7 INTO FLTO SDI SDA AN12 RBO INT1 SCK SCL AN10 RB1 INT2 VMO AN8 RB2 CCP2 VPO ANS RB3 KBIO CSSP AN11 RBA KBI1 PGM RB5 KBI2 PGC RB6 KBIS PGD RB7 T1OSO T13CKl RCO T1OSI CCP2 UOE RC1 CCP1 P1A RC2 VUSB D VM RCA D VP RC5 TX CK RC6 RX DT SDO RC7 USB Socket SPPO RDO SPP1 RD1 SPP2 RD2 SPP3 RD3 SPP4 RD4 P1B SPP5 RD5 P1C SPP6 RD6 P1D SPP7 RD7 CK1SPP ANS REO CK2SPP ANG RE1 OESPP AN7 RE2 MCLR VPP RES3 PIC18F4550 Figure 4 This is the USB serial

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